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Topic: ET 787 On Fire At Heathrow Part 6
Username: moderators
Posted 2013-07-18 17:20:00 and read 44774 times.

Hello All,

The previous thread has gotten quite large so Part 6 is being created in order to further the conversation.

Part 5 can be found here ET 787 On Fire At Heathrow Part 5 (by moderators Jul 16 2013 in Civil Aviation)

Please remember the Airliners.net forum rules when posting. Posts found in violation of the rules will be removed.

Regards,

The Moderator Crew

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: BEG2IAH
Posted 2013-07-18 17:42:14 and read 44811 times.

To repeat, the AAIB published a special bulletin:

Special Bulletin S5/2013 - Boeing 787, ET-AOP
S5-2013%20ET-AOP.pdf" target="_blank">http://www.aaib.gov.uk/cms_resources/S5-2013%20ET-AOP.pdf

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Stitch
Posted 2013-07-18 18:00:38 and read 44622 times.

To summarize the AAIB report, the source of the fire was in the area of the Emergency Locator Transmitter [ELT] and the ELT was the only device in the area that could provide a source of stored energy capable in initiating a fire. The lithium-manganese dioxide batteries in the ELT suffered damage, but it is unknown if the batteries themselves initiated the fire or if they were damaged by an external mechanism such as an electrical short. If there was a short that damaged the batteries, they could have initiated the fire. There is extensive heat damage to the upper portion of the rear fuselage with thermal damage to the insulation and structure - reported to be paint peeling and damage to the composite structure.

The ELT is self-powered. It does not receive any power from the 787's electrical system, though there is signaling wiring to the ELT. The 787 was connected to a ground power outlet at the time, but power to the outlet had been shut off. The batteries are tested on an annual basis and have a 10-year shelf life. There have been no reports of an ELT battery failing in such a way as to initiate a fire. Nonetheless, the AAIB has recommended ELTs be removed from the 787 fleet until an AD can be determined and implemented and an examination of their installation on other aircraft be performed by the FAA.

[Edited 2013-07-18 18:08:26]

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: golfradio
Posted 2013-07-18 18:21:34 and read 44378 times.

Quoting Stitch (Reply 2):
The ELT is self-powered. It does not receive any power from the 787's electrical system, though there is signaling wiring to the ELT

How is the battery charged if it is not connected to the aircraft's bus?

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: WestWing
Posted 2013-07-18 18:25:17 and read 44344 times.

Quoting Stitch (Reply 2):
the AAIB has recommended ELTs be removed from the 787

The phraseology was a recommendation to "make [the ELT] inert". I guess for a device with batteries that cannot be removed, the only way to achieve "inertness" is to remove the ELT in toto?

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Daysleeper
Posted 2013-07-18 18:26:07 and read 44325 times.

Quoting Stitch (Reply 2):
There is extensive heat damage to the upper portion of the rear fuselage with thermal damage to the insulation and structure - reported to be paint peeling and damage to the composite structure.

Does anyone know if the fuselage was breached as extensively as the photo's depict?

I'm just scanning though the report for a second time, but unless I missed a section on the first read though I can't recall it going into detail regarding the damage.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: KELPkid
Posted 2013-07-18 18:29:09 and read 44311 times.

Finally!

I was waiting fo the mods to start a new thread...

Now, according to the report:

"Surveying and detailed examinations of damaged areas revealed that the greatest heat damage and highest temperatures were centered on the rear fuselage close to the crown and displaced to the left of the aircraft centre (sp?) line. This corresponds to the most damaged external areas, with blackened and peeling paint and damage to the composite structure. It also coincides with the location of the aircraft's Emergency Locator Transmitter (ELT) and its associated system wiring which is mounted internally on the structure close to the aircraft skin. There are no other aircraft systems in this vicinity which, with the aircraft unpowered, contain stored energy capable of initiating a fire in the area of heat damage."

This means:
1). No burn through. There were no holes on the exterior of the aircraft (as per a.net speculation...).
2). If something started burning, it did so at least ~10 hours earlier. Nothing on the plane was able to initiate a fire, other than perhaps the ELT (by way of its battery).

The report confirms that ground power was disonnected. I'm sure they checked the airframe to confirm that the master switch wasn't accidentally left on  

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: KELPkid
Posted 2013-07-18 18:31:40 and read 44273 times.

Quoting golfradio (Reply 3):
How is the battery charged if it is not connected to the aircraft's bus?

It has a factory charge which is supposed to last approximately 10 years on the shelf (with regular testing intervals)... My guess is it isn't actually rechargeable, and is more akin to a dry cell battery, where once the charge is gone, the battery is discarded.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Stitch
Posted 2013-07-18 18:32:38 and read 44253 times.

Quoting golfradio (Reply 3):
How is the battery charged if it is not connected to the aircraft's bus?

They are not rechargeable. They are disposable. So after 10 years (or should they fail a test), you replace them with new ones.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Sgarr
Posted 2013-07-18 18:33:39 and read 44243 times.

This is a little out there, but is it conceivable there could be issues related to accumulated static charge creating a large potential between the aircraft hull and whatever the reference ground is for the electronics? If so perhaps a discharge through the ELT antenna kicked off the battery failure. Like I said, the idea seems far fetched, but so do other proposed causes.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: BEG2IAH
Posted 2013-07-18 18:42:33 and read 44155 times.

Quoting Daysleeper (Reply 5):
I'm just scanning though the report for a second time

You make it sound like the report is 300 pages long when it's only 3.  

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: flood
Posted 2013-07-18 18:47:25 and read 44117 times.

Quoting Daysleeper (Reply 5):
Does anyone know if the fuselage was breached as extensively as the photo's depict?

There apparently was no breach. The AAIB report which made no mention of such and Ostrower, citing a source familiar with the investigation, reported the fire didn't burn through the fuselage.
http://blogs.wsj.com/corporate-intel...roblem-taking-it-to-the-body-shop/

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: billreid
Posted 2013-07-18 19:08:47 and read 43951 times.

Quoting Sgarr (Reply 9):

I thing you are looking way to far. Chasing fantom gremlims.
We can suggest many different theories here on A.net yet there were actual professionals on board looking at what actually took place.
The statement by the authorities are pretty difinitive.

Of course I heard Elvis was upstairs smoking a fag, and he fell asleep.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: TheRedBaron
Posted 2013-07-18 19:10:52 and read 43931 times.

My post got lost on the other thread, so I reported it here sorry for the format...


Quoting 2175301 (Reply 279):
Since the ELT only emits power to the antenna if it has been triggered (and no one has reported that the ETL went into transmit mode); and should not emit any power to any of the other wires connected to the ELT from the 787 - that would indicate that something had to fail inside the ELT for power to be applied to those wires. Now, given some kind of failure inside the ELT it may be possible that a short outside the ELT also occurred which could then be the source of the fire. But, it is just as likely that if there was a short that it was inside the ELT itself with the resulting start of the fire occurred inside the ELT. The AAIB has not said where any potential short was (or most likely was) - and is continuing the investigation in the hopes of sorting this out.

Correct and let me add some pertinent questions: Does the battery inside the ELT has enough energy (joules) to generate the heat and subsequent ignition-fire...

Quoting hivue (Reply 285):
Yes, it sounds like the AAIB has yet to determine where any putative short was. A third possibility is a defective battery that overheated spontaneously.

If the Battery overheated, man this Airplane does need some exorcising, ther have been lot of those units on other aircraft and it happens in a 787 for God´s Sakes? Bad Luck?

Quoting Daysleeper (Reply 291):
I just find it incredibly hard to believe that the ELT is solely responsible for this incident, if that's writing off possibility's then yes, guilty as charged.

I find it hard to believe and if it was the real cause, those ELT are badly designed...

Quoting Klaus (Reply 294):
Battery fires are usually not fed by atmospheric oxygen but by the components of the battery itself – that is why they're so hard to extinguish.

These fires are basically the result of the charge of the battery not being turned into electical energy as it should be normally, but instead into thermal energy.

How much energy conversion does that battery has to cause so much damage....??? good question dont you think KLaus?

Quoting Klaus (Reply 314):
At least MacBooks have built-in microcontrollers in each removable battery pack plus at least one in each computer which do in fact keep track of the charging history (both current charging state and global charging / discharging cycles), computer state and so on. They are always powered as long as the power cord is connected (desktop Macs) or battery power is available (MacBooks).

It is absolutely feasible to have a similar facility in an airliner, fed by the standby/battery buses and keeping track of power usage even in the absence of ground or generator power.

Great Observation, if a Macbook of 1000 USD$ has microcontroller protection, why a multimillion aircraft lacks it?

Quoting Finn350 (Reply 318):
The AAIB report ALMOST says the following:

The aircraft Emergency Locator Transmitter (ELT) initiated fire (because it is the only system which contains stored energy capable of initiating fire with aircraft unpowered in the vicinity of the area of the heat damage ).

They have facts and they have to use logic and place the blame on the component that is near the damage and has enough energy to cause such damage... they suspect the ELT and have made recommendations, but if the remove the components on other 787 and we have another "event" what THEN?

Does somebody know how many different batteries the 787 has? because maybe they need to check all of them... just sayin´

TRB

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Daysleeper
Posted 2013-07-18 19:18:32 and read 43872 times.

Quoting BEG2IAH (Reply 10):
You make it sound like the report is 300 pages long when it's only 3

I hate it when a document has multiple columns per page, I always manage to a section no matter how long or short the document is. I've never quite understood why the format is still used outside of a newspaper.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: aklrno
Posted 2013-07-18 19:30:40 and read 43801 times.

Quoting KELPkid (Reply 6):
"Surveying and detailed examinations of damaged areas revealed that the greatest heat damage and highest temperatures were centered on the rear fuselage close to the crown and displaced to the left of the aircraft centre (sp?) line.

It's from England. Of course it is spelled "centre"!

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: cornutt
Posted 2013-07-18 19:36:56 and read 43753 times.

Quoting TheRedBaron (Reply 13):
Great Observation, if a Macbook of 1000 USD$ has microcontroller protection, why a multimillion aircraft lacks it?

I can think of a couple of reasons: One is the need to certify that circuitry, and whatever software is embedded within it. Here's a problem that people are running into when they try to build avionics with off-the-shelf components: In order to get the hardware and/or software certified, you need access to design information and source code, and also to process documentation from the development process. In a lot of cases, for COTS components, the process documentation is lacking or doesn't exist at all, and the vendor has no interest in releasing their intellectual property for the purpose of certification. They look at and say, "We might sell 1000 of these to the avionics market, but we can sell 10 million of them to the phone manufacturers. So if we have to go out of our way even a little bit for the avionics market, screw it."

The other problem with the COTS battery manager is that they have a nasty habit of shutting off the battery when they *think* the charge is sufficiently depleted. We've all had the experience with laptops and tablets and so forth, that when the battery starts to age a bit, the available time on a battery charge drops abruptly. Transient conditions can trick those battery manager controllers into thinking the battery capacity has been greatly reduced. Obviously this is not what you want with an ELT; if and when the battery is needed for its intended purpose, you want that damn thing to keep discharging down to the last electron.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Stitch
Posted 2013-07-18 19:38:19 and read 43754 times.

Quoting TheRedBaron (Reply 13):
Great Observation, if a Macbook of 1000 USD$ has microcontroller protection, why a multimillion aircraft lacks it?

It's irrelevant in the case of the ELT battery since it is not rechargeable.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Klaus
Posted 2013-07-18 19:39:36 and read 43746 times.

Quoting Sgarr (Reply 9):
This is a little out there, but is it conceivable there could be issues related to accumulated static charge creating a large potential between the aircraft hull and whatever the reference ground is for the electronics? If so perhaps a discharge through the ELT antenna kicked off the battery failure. Like I said, the idea seems far fetched, but so do other proposed causes.

Shouldn't happen, since signal reference ground should be connected to the fuselage (embedded mesh in this case).

And the ground power connector should also have tied the whole system to actual ground, even while the actual power supply remained switched off according to the engineer.

Quoting billreid (Reply 12):
The statement by the authorities are pretty difinitive.

Not this one – this is very clearly and explicitly just a provisional "Special Bulletin".

It draws no definitive conclusions at all.

Quoting TheRedBaron (Reply 13):
How much energy conversion does that battery has to cause so much damage....??? good question dont you think KLaus?

About as much as the electrical charge it can hold. Depends on circumstances and the chemical makeup.

An important variable dependent on the construction of the battery is the speed and thus violence of a battery failure (the cobalt-based Li-Ion main batteries are pretty much at the top of that ranking).

Quoting TheRedBaron (Reply 13):
Great Observation, if a Macbook of 1000 USD$ has microcontroller protection, why a multimillion aircraft lacks it?

I don't say it does – it's quite possible the 787 have permanent power monitoring facilities built in. It would be quite a bit more complex for an airplane than for a notebook computer, though.

Active power monitoring should be present in any case – it's necessary for safe operation to keep track of how much power is consumed where and to kick off some less critical consumers (load shedding) when power supply is strained (for instance when some of the generators go offline).

Quoting Stitch (Reply 17):
It's irrelevant in the case of the ELT battery since it is not rechargeable.

That's not the point – if the ELT (or a related component) should have been cooked with power from the main supply due to a short, such fault currents would most likely turn up in the log of a power monitor.

[Edited 2013-07-18 19:43:30]

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: hivue
Posted 2013-07-18 20:35:00 and read 43491 times.

Haven't seen this posted yet from Reuters:
http://finance.yahoo.com/news/dreaml...robe-focuses-beacon-174527528.html

"Boeing's new plane has a relatively high humidity, which helps keeps (sic) passengers more comfortable, and investigators are now looking at whether there is enough insulation to prevent moisture from condensing and short circuiting systems such as the beacon, said the source, who was not authorized to speak publicly.

"A source close to Boeing, speaking on condition that he not be named, said the 787 may need better isolation of electrical components from the plane's high humidity, something industry people refer to as 'rain in the plane.'"

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Stitch
Posted 2013-07-18 21:01:10 and read 43319 times.

Quoting Klaus (Reply 18):
That's not the point – if the ELT (or a related component) should have been cooked with power from the main supply due to a short, such fault currents would most likely turn up in the log of a power monitor.

But based on the post of an employee of a 787 operator, it appears the ELT is not near any power conduits. So could such an event happen? Does anyone know the voltage and current of the wires that are connect the ELT to the cockpit?


The condensation issue is an interesting one. Is the ELT installed underneath the fuselage or in a blister on top?

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: airtechy
Posted 2013-07-18 21:09:18 and read 43269 times.

As I said in an earlier post, the ELT is mounted directly under it's antenna in the upper fuselage. You want the antenna to be on top so it can radiate and you want the connection to the antenna to remain intact if the airplane gets torn apart in a crash.

AT

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: KELPkid
Posted 2013-07-18 21:32:31 and read 43150 times.

Quoting hivue (Reply 19):
"Boeing's new plane has a relatively high humidity, which helps keeps (sic) passengers more comfortable, and investigators are now looking at whether there is enough insulation to prevent moisture from condensing and short circuiting systems such as the beacon, said the source, who was not authorized to speak publicly.

"A source close to Boeing, speaking on condition that he not be named, said the 787 may need better isolation of electrical components from the plane's high humidity, something industry people refer to as 'rain in the plane.'"

Well, the crown of an aircraft, baking in the sun, on a hot afternoon is not exactly a condusive environment for condensation to form...

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: gators312
Posted 2013-07-18 21:52:24 and read 43009 times.

Could a lightning strike in flight to the ELT antenna have begun the thermal runaway of the battery inside the ELT?

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: seahawk
Posted 2013-07-18 22:40:29 and read 42490 times.

It must be some kind of special bad luck, when on a new auirplane you get thermal events on 3 different batteries in 3 different incidents.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Ruscoe
Posted 2013-07-18 23:25:18 and read 43503 times.

Currently the two things I find most interesting are;

1. Boeing is saying that the ELT is a customer option item

and

2. The AAIB is recommending to the appropriate authorities that all Lithium based batteries in ELT's be looked at, which obviously includes a lot of aircraft from all manufacturers

Ruscoe

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Speedbored
Posted 2013-07-18 23:38:14 and read 43653 times.

Hi from a long-time lurker who's not previously been allowed to post due to contractual obligations working for an employer paranoid about protecting client confidentiality. Now that I am semi-retired, however, it's probably time to start contributing. Here's hoping I don't live to regret it.  

Just for the record, I would like to point out that I am neither an Airbus fanboy nor a Boeing fanboy. I am simply interested in aviation, regardless of manufacturer, having worked in and around the industry for just over 25 years.

Having read the AAIB special bulletin very carefully, the only definitive conclusion that I've been able to come to based on it is that there was a fire on an Ethiopian 787 at Heathrow (which I knew already). It seems to me that many people are reading a lot more into the bulletin than is actually there. What we all need to bear in mind is that the AAIB press release and special bulletin are both very very carefully worded so as to avoid drawing any conclusions at all at this stage. The investigators are keeping their minds open and so should we.

For example, the holes in the fuselage question. The AAIB simply says that there is "damage to the composite structure". So this damage may or may not include holes penetrating the skin. The fact is we simply don't know at the moment. I have to admit that from the public images I have seen, I struggle to see how some of the very black patches can be anything other than holes, but I'm content to wait for more information from the AAIB to find out for sure.

Then there's the source of the fire. It seems that a lot of people are reading the AAIB bulletin as saying that it started in the ELT battery, either caused by a fault in the ELT itself or as a result of an external short. I would agree that is what it infers if the fire started while the aircraft was "unpowered". But the inclusion of the "with the aircraft unpowered" statement in this part of the bulletin suggests to me that the AAIB are still entertaining the possibility that the fire could have started while the aircraft was "powered", so the energy to start the fire could have come from elsewhere. I know that it's been stated very firmly by some people that there are no power cables to the ELT, so the energy could not have come from elsewhere, but there are 4 (or was it 3?) data cables connecting to the ELT and a data cable will become a power cable if you apply power to it. Perhaps there was a fault in the flightdeck control panel or a data concentrator, or a short between a data cable and a nearby power cable or one of the many connectors somewhere en-route.

I'm of the opinion that it's entirely plausible that the fire could have started a long time before it was noticed by the control tower, possibly even while external power was still on, many hours earlier. There are a lot of flame resistant (as opposed to flameproof) materials on an aircraft and many of these can smoulder for a very long time before sufficient heat builds up to sustain a proper fire.

So, again, I think we need to keep an open mind on the source of the fire until we get more information. The AAIB certainly seems to be doing so: "Detailed examination of the ELT and the possible mechanisms for the initiation and sustaining of the fire in this aircraft continues."

The rumour about condensation is interesting. My understanding of condensation is that it mostly forms at altitude in the form of ice on the inner skin of the aircraft which then melts after landing to form the water that gets blown around by the aircon or tipped out of the ceiling panels on take-off. Certainly seems plausible that ice could have formed in or around the ELT at altitude, or in or around any of the cable bundles and connectors, causing a short when it later melted. Perhaps water running down cable bundles into the power panels or other electronics could explain some of the other issues that have occurred. Might explain why the culprit has been hard to find - it evaporated.

The thing that I find most interesting in the special bulletin, however, is the safety recommendations. I'm surprised that noone else has picked up on it yet but I suspect that Boeing might be more than a little concerned about the fact that the AAIB is only recommending inerting the roughly 1% of these ELTs that are installed on 787s. Without wanting to jump to any unwarranted conclusions, I can't help wondering why, if the AAIB has concluded that the ELT is a risk, they have not also recommended that all 6000 of them are inerted on every aircraft type. Why do the other 99% only warrant a "safety review"? Food for thought.

Personally, I'm keeping an open mind as to whether or not there's any underlying systemic issue with the 787. With the small number of incidents so far, and the lack of confirmed information as to their underlying causes, it's impossible to be certain one way or another right now. Could be a problem with the system or could just be bad luck. But it sure is fun reading all of the discussions about it in the very many threads.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Pellegrine
Posted 2013-07-18 23:46:34 and read 43872 times.

Quoting Speedbored (Reply 26):

Thank you! This was my point earlier...the AAIB bulletin does not say anything of note. I am a lover of the aviation industry overall... It is very hard to believe an ELT battery produced enough sustained power to initiate this damage. It's like a smoke detector burning down a house.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: flyglobal
Posted 2013-07-18 23:48:34 and read 43815 times.

I don't believe so much in bad luck.

Having seen electronic devices behavior different depending on environment and built in conditions in car industrie, my engineering experience tells me that it may have to do something in with the speific built in / environment conditions in the 787.
So any failure analysis I would start with: Lets check what is different and probably unique in the 787 to other airplanes.

Starting:
1) Composite instead of metal
2) Humidity higher then all other planes before.
3) Ventilation situation around the ELT ower then in other planes?

Special conditions at the day of incidence:
Very high otside temperatures
Probably humidity left when the plane was sent to parking position?

Make a Lab test with the 787 conditions inside the plane as expected:
Humidity and tempereture - 8h in the burning sun? getting the battery to about 60°C +? In humidity of ??.

Anyhow again: My engineering brain and gutt feeeling points me to this.

regards

Flyglobal

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Finn350
Posted 2013-07-19 00:20:38 and read 43407 times.

Quoting Speedbored (Reply 26):
I can't help wondering why, if the AAIB has concluded that the ELT is a risk, they have not also recommended that all 6000 of them are inerted on every aircraft type

Well written post. And the recommendation regarding the safety review of ELTs installed in other aircraft types covers ALL Lithium-powered ELTs, not just those manufactured by Honeywell.

The AAIB report is quite clear on ELT being the initiator of the fire (only "loopholes" mentioned are if the aircraft was powered, fire started when the aircraft was powered, or fire started outside the area of the heat damage, which all sound quite implausible).

The report specifies two different possible initiators to the combustion: either the ELT battery itself or an electrical short powered by the ELT battery (and leaves open there might be other initiators besides an electrical short in case of an external mechanism to ELT). What I find hard to see how an electrical short among the few cables that come out of the ELT could lead to an ignition, no matter how you short those cables.

Regarding the root cause, the AAIB report does not speculate at all on that.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Speedbored
Posted 2013-07-19 00:31:01 and read 43230 times.

Quoting flyglobal (Reply 28):

I can't see it being temperature - Lithium Manganese Dioxide batteries are usually rated to at least 60°C so I doubt that there would be any likelihood of temperature causing spontaneous combustion until well over 90°C. And there are loads of these batteries in ELTs on top of aircraft operating from far hotter airports than Heathrow, and with darker bodywork, with no issues.

I agree that the humidity/condensation issue probably warrants further investigation but, as has been stated by others earlier, there have been many instances of water flowing from ceilings in other aircraft without it causing issues. Is there something very different about the way wiring and connections are done in a 787?

Composite instead of metal? That's one area where I think there could be issues. Previous metal aircraft have relied on the aircraft structure to provide a common earth for the electrics and electronics. Obviously, this isn't possible with non-conducting composite, which is why Boeing have added a metal mesh to the structure. I can't help wondering whether something went wrong with the earthing of the ELT. I do not know how Boeing ensures that the electrical earth is properly connected but if they are relying on rivets or bolts making contact with a mesh at some point, I can see how it may have failed to connect, especially if the ELT has been removed and replaced at some point. If improperly earthed, the ELT antenna would be ideally placed to build up a significant static charge, given its location sitting out there in the slipstream. And the only way for that charge to discharge itself would be via the electronics and data cables, which could cause trouble.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: LTC8K6
Posted 2013-07-19 00:31:42 and read 43185 times.

Why would there be high humidity when it's parked? The "high humidity" for pax is when the plane is flying, provided by the aircon system.

The "high humidity" in the 787 is something like 15% at a cabin altitude of 6K feet, just like the newest airbuses, iirc.

So it's hardly what you'd call high humidity, if you weren't in an airplane.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: RedChili
Posted 2013-07-19 00:40:21 and read 43186 times.

Quoting Speedbored (Reply 26):
Hi from a long-time lurker who's not previously been allowed to post due to contractual obligations working for an employer paranoid about protecting client confidentiality. Now that I am semi-retired, however, it's probably time to start contributing. Here's hoping I don't live to regret it.

  

One of the best posts so far in this entire discussion!

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Speedbored
Posted 2013-07-19 00:41:48 and read 43075 times.

Quoting Finn350 (Reply 29):
The AAIB report is quite clear on ELT being the initiator of the fire (only "loopholes" mentioned are if the aircraft was powered, fire started when the aircraft was powered, or fire started outside the area of the heat damage, which all sound quite implausible).

I agree that the report seems to be hinting very strongly at the battery being the source (though not necessarily the cause) of the fire. But the AAIB is deliberately avoiding saying so as there are still many other possibilities to discount, however implausible they might be.

Quoting Finn350 (Reply 29):
What I find hard to see how an electrical short among the few cables that come out of the ELT could lead to an ignition, no matter how you short those cables.

I also fail to see how shorting out two data cables could cause a problem. It probably happens many times a day in offices all over the world without problems. I'm guessing that they are suggesting the possibility of a short between one of the data cables and some other cabling with a bit more oomph.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Speedbored
Posted 2013-07-19 00:47:04 and read 42982 times.

Quoting RedChili (Reply 32):
One of the best posts so far in this entire discussion!

Well, thank you.

One lesson I learnt many many moons ago was to engage brain before speaking (or typing these days). Sadly, it seems to be a lesson that quite a few people who post here have yet to learn.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: seahawk
Posted 2013-07-19 00:48:13 and read 42925 times.

I am not sure if we can be sure that the ELT started the fire. Obviously the battery can be a source of flamable material to keep a fire going, but is it strong enough to work through its containment and then ignite flame resistant materials? This would the third battery containment failure in the 787. My gut says, this is unlikely to be bad luck.

[Edited 2013-07-19 01:31:24]

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Speedbored
Posted 2013-07-19 01:00:27 and read 42760 times.

Quoting seahawk (Reply 35):
I am not sure if we can be sure that the ELT started teh fire.

I agree, we can't. But we also can't be sure that it didn't.

The only thing we can be sure of is that we're not sure.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Faro
Posted 2013-07-19 01:07:37 and read 42750 times.

Is the following understanding re the 787 incidents accurate:

- The exact cause of the JL/NH 787 battery thermal runaway is not known with 100% certainty but the measures taken to contain any such occurence in the future are sufficient to meet regulatory safety requirements; and

- The exact cause of the ET 787 rear fuselage crown fire is not known with 100% certainty but the measures which may be envisaged to prevent any such occurence in the future (presumed source of fire = ELT => removal of the ELT) would be sufficient to meet regulatory safety requirements.

If this is correct, I would imagine that Boeing engineers are looking very very hard at the the design -if not design philosophy- of the underlying 787 electrical system to ensure that it does not harbour an unknown, systemic risk...

One more electrical-related problem with the 787 and we may see more drastic measures taken by both Boeing and the regulators than a formal investigation...


Faro

[Edited 2013-07-19 01:43:53]

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: sankaps
Posted 2013-07-19 01:30:17 and read 42435 times.

Quoting flyglobal (Reply 28):
Special conditions at the day of incidence: Very high otside temperatures

I think this is more of a red herring.... the high in London that day was around 30-31C -- hot for London maybe, but positively mild relative to places like Dubai, Doha, Delhi, Dallas where 787s and other ELT-equipped aircraft freely operate. Temperatures in those places can get to 45C or higher.

Quoting Speedbored (Reply 30):
I can't see it being temperature - Lithium Manganese Dioxide batteries are usually rated to at least 60°C so I doubt that there would be any likelihood of temperature causing spontaneous combustion until well over 90°C. And there are loads of these batteries in ELTs on top of aircraft operating from far hotter airports than Heathrow, and with darker bodywork, with no issues.

Exactly.

[Edited 2013-07-19 02:01:11]

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: katekebo
Posted 2013-07-19 02:29:21 and read 41808 times.

I find all these posts that say

Quote:
I can't believe that the ELT battery could start a fire

laughable.

There is enough energy in a small chemical battery to start a fire. It's a fact and there are documented cases of this happening in all kinds of device. People who say that even a "cheap" iPhone has protection against it don't know what they are talking about. Yes, most electronic devices have protection circuits to prevent overcharge, short circuits, etc. And every day these types of circuits fail. $hit happens. Just Google "iPhone on fire" and you will find dozens of examples of iPhones that have burned spontaneously. And iPads. And Blackberries. And many other phones, computers, etc. The only difference is that when an iPhone burns, nobody talks about. An ELT in an airplane catches fire and it's front page news.

People love conspiracy theories and will disregard any evidence that contradicts their beliefs. People believe all kinds of stupid things. 40% of the people in the US do not believe in evolution, in spite of overwhelming evidence. Many believe that the Earth is 6000 years old. And many will believe that B787 is unsafe. You just can't argue with idiots.

Sorry for venting, but being and engineer and scientist, who uses data and EVIDENCE as basis for my work every day, I am tired of people who argue "yes, the evidence is, but I BELIEVE ...". Stop BELIEVING and start REASONING.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: seahawk
Posted 2013-07-19 03:33:03 and read 41023 times.

But if a fire sock is enough to contain a laptop battery, I wonder how the ELT (which must withstand 1100° for 2 minutes and still work) managed to cause a fire that was able to spread in an area made of fire retardent or resistent materials.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Speedbored
Posted 2013-07-19 03:43:28 and read 40912 times.

Quoting seahawk (Reply 40):
But if a fire sock is enough to contain a laptop battery, I wonder how the ELT (which must withstand 1100° for 2 minutes and still work) managed to cause a fire that was able to spread in an area made of fire retardent or resistent materials.

The ELT is only required to prevent a fire from getting in for 2 minutes. As far as I'm aware, there is no requirement for it to withstand a fire trying to get out. I suspect that the pressure produced by a battery fire inside the ELT will easily breach whatever vessel is used to keep fire out.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: ZB052
Posted 2013-07-19 03:50:16 and read 40812 times.

Quoting katekebo (Reply 39):
People love conspiracy theories and will disregard any evidence that contradicts their beliefs. People believe all kinds of stupid things. 40% of the people in the US do not believe in evolution, in spite of overwhelming evidence. Many believe that the Earth is 6000 years old. And many will believe that B787 is unsafe. You just can't argue with idiots.

Sorry for venting, but being and engineer and scientist, who uses data and EVIDENCE as basis for my work every day, I am tired of people who argue "yes, the evidence is, but I BELIEVE ...". Stop BELIEVING and start REASONING.

"There is none so blind as those who will not see"..............

I believe that this phrase is VERY pertinent in this situation. From BOTH sides - the 'Head in the Sanders' and the 'Sky is Fallingers'. The truth will out eventually. As you so elequently put above - evidence is the key. However, the current evidence is not categorical, no final recoomendations have been made, and the investigation is still ongoing. Therefore i find your 'vent' a little hypocritical - could you not level the same arguments to those who think that there is not an issue with the airplane?

Why do some people (on both sides) want to play judge, jury and executioner so badly??

Human nature? Payback? Bitterness? Who knows.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: oldeuropean
Posted 2013-07-19 03:56:38 and read 40739 times.

Quoting ZB052 (Reply 42):
Human nature? Payback? Bitterness? Who knows.

Don't mess with holders of Boeing shares, here on a.net.  

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: FlyingAY
Posted 2013-07-19 04:02:14 and read 40661 times.

Quoting katekebo (Reply 39):
There is enough energy in a small chemical battery to start a fire. It's a fact and there are documented cases of this happening in all kinds of device. People who say that even a "cheap" iPhone has protection against it don't know what they are talking about.

I'm sure there are more iPhones (not mentioning other consumer electronic devices) on every flight than there are ELTs, yet no iPhone in the cabin has caused such an extensive damage to a plane.

Of course you cannot compare consumer electronics with aviation components, but keep in mind that there are a few thousand ELTs with Lithium batteries that are used in very stable and predictable environments and then there are more than 100 millions of iPhones that are being used by the consumers in all kinds of ways imaginable in all kinds of places imaginable. Considering this I can accept that a few iPhones burn every now and then, but I cannot accept that an ELT ignites a fire in a plane in a way that makes AAIB write "had this event occurred in flight it could pose a significant safety concern and raise challenges for the cabin crew in tackling the resulting fire."

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: seahawk
Posted 2013-07-19 04:11:26 and read 40517 times.

Quoting Speedbored (Reply 41):
The ELT is only required to prevent a fire from getting in for 2 minutes. As far as I'm aware, there is no requirement for it to withstand a fire trying to get out. I suspect that the pressure produced by a battery fire inside the ELT will easily breach whatever vessel is used to keep fire out.

Yet is a fully enclosed aluminium case, that is carsh resistant, fire resistant, water proof and held together by screws. Add the fact that the type of batteries in the Honeywell ELT of the 787 is not only used in Honeywell ELTs on other aircraft, but also by Pointer ELTs too. (and probably many other) That is probably 10.000 units or more. And the first recorded thermal event happens in a 787. The same plane which had thermal events on other batteries, also enclosed in an aluminium case at the time those events happened. As an engineer I find that unlikely. Maybe condesation water could really be pointing into the correct direction, with the water collecting inside the aluminium cases and causing a short in the battery.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: LTC8K6
Posted 2013-07-19 04:40:54 and read 40094 times.

Looks like that ELT uses 5 of these cells according to various web sites:

http://ultralifecorporation.com/be-m...oducts/cylindrical/U10013-CR34610/

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: sphealey
Posted 2013-07-19 04:58:10 and read 39812 times.

Quoting FlyingAY (Reply 44):
I'm sure there are more iPhones (not mentioning other consumer electronic devices) on every flight than there are ELTs, yet no iPhone in the cabin has caused such an extensive damage to a plane.

Here's a link that will lead you to the FAA's guidelines and training materials for fighting a lithium battery fire in the cabin. It is a matter of some concern to both the FAA and NTSB given the rapid growth of lithium chemistry devices over the last 5 years:

http://www.faa.gov/other_visit/aviat...all_safos/media/2009/SAFO09013.pdf

sPh

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: sphealey
Posted 2013-07-19 05:02:43 and read 39813 times.

While I'm linking things   Here's a calculator for estimating the fusing (melt-through) current for copper wire at various gauges. For 24 gauge solid wire (instrument wire) I get a 5-second melt-through current of ~29 amps.

http://www.cirris.com/testing/resistance/fuse.html

sPh

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Speedbored
Posted 2013-07-19 06:09:40 and read 38973 times.

Quoting seahawk (Reply 45):
As an engineer I find that unlikely.

With the information available to me at present, I can't disagree with you or anyone else who says that it looks like there might be a systemic issue with the 787. But I'd also find it a bit difficult to disagree with anyone who claims the 787 is fine. I simply don't have enough information to be certain either way right now.

Personally, I don't feel that the 787 is significantly more dangerous than other aircraft but then I do have the luxury of not having any travel planned this year on routes served by the 787. Maybe I'd feel differently if I did, and I'm certainly not going to berate anyone for not wishing to "take the risk".

Given that the most recent event is different in a number of respects from the first two, it looks to me that the three fire or "fire-like" issues so far can just about be accommodated within the normal bounds of probability. Once-in-a-million-flight-hours doesn't have to mean that there will be a million event free hours before the first event, nor that there must be a million hours between the first and second events. Another event happening this year, however, might make the statisticians think twice.

Just for discussions sake, if we hypothetically assume that there is a systemic issue behind these events, what could possible causes be? Condensation has already been mentioned. I can think of a few others but without detailed designs, construction records and investigation results, cannot hope to even guess at how likely, or otherwise, they might be:

1) Electrical Earth Bonding.
I've been reading recently in other threads how Airbus are investing a lot of time and money in ensuring that the A350 has a good earthing skeleton, both for lightning protection and for earth bonding of the electrical systems. I presume that Boeing did the same during 787 development and I also assume that Airbus will have learnt many lessons from what Boeing has done. Unlike a metal plane where the earthing system gets joined up simply by assembling the aircraft, with a CFRP frame, there will necessarily be many points at which the various metal parts of the earth bonding skeleton need to be electrically connected together. I can't help wondering, however, why Airbus didn't include some CFRP into the iron bird to test electrical bonding during their system tests.

Aircraft are very good at building up static charges, and I suspect that plastic aircraft are even better at it. If any of the earth bonding connections are missing due to bad design, or mis-assembly (perhaps loose, or assembled with dirt in the connection) then there will be a very good possibility of high voltage static charges building up in some parts of the electrical system, which could then, when something switches on or off, be suddenly discharged via very unpredictable routes through sensitive equipment (electronics, maybe batteries), causing damage which could trigger events such as we've seen.

2) Voltage spikes.
It's no secret on Anet that Boeing might have made some mistakes on the outsourcing of the design and development of the electrical system. I get the impression that Boeing designed the system at a high level and then delegated the detailed design and development of individual parts of the system to many different contractors and subcontractors. I can't help wondering whether this might have led to the development that of lots of subsystems that work well in isolation but maybe have issues when interacting with one another.

In any electrical system with things regularly switching on and off, voltage spikes will be created by the switching, even when using solid-state switches. These spikes are usually smoothed out using accumulator devices such as capacitors or magnetic coils. As accumulator devices contain a lot of metal, they are heavy, so I can see why some of the subsystem developers might have taken the approach of "we'll assume that the signals and power that we get will be smooth" to keep the weight of their own sub-assemblies down. i.e. assume it's someone else's problem to smooth out the spikes. And, as Boeing only concerned themselves with the high level design, maybe they didn't pay much attention to this until it was too late. Or maybe any spikes they found during testing were insignificant enough to not cause damage. Perhaps the spikes only get sufficiently large to cause damage when a flap motor, a toilet flusher, an oven and a coffee pot all switch off at the same time. So perhaps it was the coffee pot's fault after all.  

And finally, as they say on the other side of the pond, the "curveball". I suspect that I'll probably get laughed at for this one but I don't think it's completely outside the realms of possibility, so bear with me on this:

3) Vibration.
And I'm not talking the sort of vibrations the aircraft manufacturers try to get rid of during flutter testing. I'm talking about the low level "humming" type vibrations caused by the engines or A/C power buses.

After the first battery meltdown, and seeing how the battery was constructed, I couldn't help wondering whether sudden shocks or vibrations might cause the electrodes or electrolyte to move around within the battery, and possibly cause a short. I then got wondering about the difference between aluminium and CFRP in terms of absorption of low level vibrations. My guess is that metal, being softer, will absorb more of the vibrations than CFRP which, being more rigid, probably passes on the vibrations to be absorbed by softer materials elsewhere like seat cushions, bodies or battery electrolyte, perhaps?


Would be interested to hear what other people's thoughts are.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Daysleeper
Posted 2013-07-19 06:30:15 and read 38568 times.

Quoting Speedbored (Reply 30):
Is there something very different about the way wiring and connections are done in a 787?

The 787 uses a distributed power system, with multiple RPDU's (sorta like substations) throughout the aircraft. As far as I'm aware this system was introduced with the 787 and is unique.

Quoting oldeuropean (Reply 43):
on't mess with holders of Boeing shares, here on a.net.

The smoke was still clearing when Boeings stock price was being discussed on here...

[Edited 2013-07-19 07:03:27]

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Finn350
Posted 2013-07-19 06:35:41 and read 38462 times.

Quoting LTC8K6 (Reply 46):
Looks like that ELT uses 5 of these cells according to various web sites:

http://ultralifecorporation.com/be-m...4610/
Quoting sphealey (Reply 47):
Here's a link that will lead you to the FAA's guidelines and training materials for fighting a lithium battery fire in the cabin. It is a matter of some concern to both the FAA and NTSB given the rapid growth of lithium chemistry devices over the last 5 years:

http://www.faa.gov/other_visit/aviat...3.pdf

Those are good links both. It might be that end result of this investigation is to propose reverting back to Ni-Cd (Nickel-Cadmium) batteries instead of Lithium-Ion batteries in future applications (as Airbus already did with A350 primary & APU batteries).

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: bikerthai
Posted 2013-07-19 06:51:25 and read 38069 times.

Speedbored,

Good to hear from an old timer. Just one suggestion. Break up your posts. A long post with many interesting questions is difficult to follow and respond.

Let me try to respond to stuff that I know.

1) Humidity in the plane: Even though the 787 has higher humidity, it does not significantly increase the effect of the phenomenon known as rain in the plane. There are videos examples of rain in the plane for aluminum aircraft. Condensation will occur on a plane metal or composite (full of people or not) and design have to taken into consideration to address it. In this case:
a) the insulation blankets on the crown of the plane should divert the condensation on the hull to the side of the aircraft and down to the bilge.

b) wiring would have been routed such that any condensation dripping down the wire from the antenna would drip off before approaching the connector to the ELT.

c) The connector themselves have seals and gaskets at the pins and receptacles to keep moisture from entering the ELT

d) The ELT would probably be sealed from moisture (maybe some protected venting?)

e) External grounding connection (if any) would be sealed with goop sealant to prevent moisture related corrosion.

These are general design practice in the industry and most likely would have been applied to this situation.

bt

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: bikerthai
Posted 2013-07-19 07:09:09 and read 37709 times.

Quoting Speedbored (Reply 49):
1) Electrical Earth Bonding.

Grouding/Bonding - Static Discharge.

Not to minimize the this design issue, but grounding and static discharging of CFRP composite is a known quantity. It have been applied to the 777 tail for 20+ years.

Heck, while it's not CFRP, the floor panels all current commercial aircraft in production are made of glass reinforced plastic. Even the carpet in the airplane have to take static discharge in to account. And some exterior paint include anti-static properties.

So, from the design side, these things are taken into consideration. However, from the execution side, I do not want to go there with deference to another a-net old timer  

bt

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: hivue
Posted 2013-07-19 07:11:59 and read 37667 times.

Quoting Speedbored (Reply 26):
The thing that I find most interesting in the special bulletin, however, is the safety recommendations. I'm surprised that noone else has picked up on it yet but I suspect that Boeing might be more than a little concerned about the fact that the AAIB is only recommending inerting the roughly 1% of these ELTs that are installed on 787s. Without wanting to jump to any unwarranted conclusions, I can't help wondering why, if the AAIB has concluded that the ELT is a risk, they have not also recommended that all 6000 of them are inerted on every aircraft type. Why do the other 99% only warrant a "safety review"? Food for thought.

This issue was raised in part 5 of this thread. It got the poster tagged by a few people as a suspected 787-basher.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: hivue
Posted 2013-07-19 07:26:11 and read 37354 times.

Quoting katekebo (Reply 39):
Stop BELIEVING and start REASONING.

Many beliefs turn out to be worth nothing, but every well-reasoned, accepted scientific theory began life as a belief.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Ty134A
Posted 2013-07-19 07:26:52 and read 37379 times.

If condensation is such a big issue to new planes, I guess it might be one to older ones as well, but it never has been. If I take my three trips on the Yak-42 2 weeks ago, it was litterally raining in the cabin and from the overhead vents! See for yourself the videos below I shot:

http://www.youtube.com/watch?v=4cAnVSI9zQA (all the humidity from the airconditioning formed into condensation during flight and upon landing, it was not only humid, but wet all over the place!!!)

http://www.youtube.com/watch?v=urC374qylcQ (in the end of this video you can see drops running along the ceiling, as well as lots of water sprinkeling through the airconditioning!!!)

I think that if Yaks fly soaked in water, I feel that this should not be an issue to the B787, since it is a new airplane! I have a strange feeling about the Dreamliner and do not hezitate to get on one at this point!

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Speedbored
Posted 2013-07-19 07:39:36 and read 37194 times.

Quoting hivue (Reply 54):
This issue was raised in part 5 of this thread. It got the poster tagged by a few people as a suspected 787-basher.

Well if making perfectly reasonably points and asking perfectly reasonable questions about safety recommendations made by the AAIB makes some people consider me a 787-basher then so be it. Nothing could be further from the truth. I've been more than fair to the 787 in the posts I've made so far.

But I never expected that I'd please all of the people all of the time.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: ODwyerPW
Posted 2013-07-19 07:46:44 and read 37129 times.

Quoting katekebo (Reply 39):
People love conspiracy theories and will disregard any evidence that contradicts their beliefs. People believe all kinds of stupid things. 40% of the people in the US do not believe in evolution, in spite of overwhelming evidence. Many believe that the Earth is 6000 years old. And many will believe that B787 is unsafe. You just can't argue with idiots.
Sorry for venting, but being and engineer and scientist, who uses data and EVIDENCE as basis for my work every day,

Your arrogance is disturbing. I look at the evidence and draw an entirely different conclusion. Sir, I am no idiot. Even the most analytical of minds can be influenced by a bias that alters their interpretation/analysis of evidence leading them to draw still different conclusions. Get over yourself.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: LTC8K6
Posted 2013-07-19 07:53:54 and read 36912 times.

I would say these batteries have plenty of energy to start the fire as described.

http://ultralifecorporation.com/download/353/

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: 777Boeing777
Posted 2013-07-19 08:01:56 and read 36813 times.

Quoting Speedbored (Reply 57):
Well if making perfectly reasonably points and asking perfectly reasonable questions about safety recommendations made by the AAIB makes some people consider me a 787-basher then so be it. Nothing could be further from the truth. I've been more than fair to the 787 in the posts I've made so far.

It's not about anyone being a 787-basher because they discuss FACTS that have come out, and nobody is in any way accusing you of that. What I find absurd is that there is a blatant disregard for FACT, and this series of 787 threads is proof positive of that. For example, the AAIB comes out and says that they have no evidence that the fire was linked to the earlier 787 battery problems, yet apparently some on here feel they are the armchair engineers and know better than the investigators. I've been reading these forums for 3+ years, and at times have had to go look elsewhere because I got tired of trying to discern the facts and good info through all of the white noise and useless banter (which there is way to much of). Thankfully, there are a handful of level-headed knowledgeable and unbiased posters on here, such as Stitch, who are a wealth of information.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: sankaps
Posted 2013-07-19 08:18:19 and read 36440 times.

Quoting 777Boeing777 (Reply 60):
For example, the AAIB comes out and says that they have no evidence that the fire was linked to the earlier 787 battery problems

There is no evidence **yet** (and it may in fact turn out that there is no linkage to the issues that resulted in the earlier fires), but the investigation is not over, they still do not know what caused it, and whether there may turn out to be a common root cause (which would frankly be a best case outcome, rather than multiple different unconnected reasons for these fires).

Some people take this to mean this latest incident has nothing to do with the 787 and everything to do with the ELT alone, when logic and odds would suggest otherwise.

The fact is both the 787 and the ELT (and the interaction between the two) are currently under investigation for this, otherwise the AAIB would not have stopped at recommending that only the 787's ELTs be inerted while the others can continue to be active after an inspection.

I know I am thought of by some as being a 787 basher because of this point of view. But to me this is an entirely fact-based, unemotional, and logical conclusion based on what it known to date.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: nm2582
Posted 2013-07-19 08:32:27 and read 36231 times.

Did a bit of research this morning that I thought I would share. I was curious if the cells used in the ELT used the same lithium chemistry as any other common lithium cells.

It's been mentioned earlier in this thread that the ELT uses CR34610 cells - I have not confirmed this myself.

The CR34610 cell (as has been widely reported) is lithium manganese dioxide. My research indicates that this is the same chemistry that is used in the CR123 cell - a very widely used cell in (among other things) older film cameras and certain modern LED flashlights.

For size comparison - The CR34610 is about the size of a common flashlight "D" cell battery (or at least that's the designation we use in USA - I'm not sure if different countries use a different designation). The CR123 is much smaller (and thus contains less energy).

In the LED flashlight community, there is an awareness that CR123's can be unstable and fail (sometimes with significant energy output) in certain situations. For a while, there was a significant problem with counterfeit and poorly made CR123's. At least two known failure modes exist: (1) the cell case seal can fail, allowing air into the cell (or whatever else is in the environment around it that is able to make it through the failed seal). Containing lithium metal, the cells can react quite violently to this if (for example) moisture gets in. (2) if multiple cells are used in series (some LED flashlights can use 2, 3, or more CR123's in series) and one cell has a lower state of charge that differs from the others, the lowest cell can fail once it has discharged but the other cells continue to force current through it.

These failure modes are quite replicable and people in the LED flashlight community have done home experiments to replicate them.

I do not know if the physical construction of the CR34610 cell is similar to a CR123, but my assumption is that it is. I would assume that (being used in aviation) it is held to higher standards, has better seals, etc.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: hivue
Posted 2013-07-19 08:35:52 and read 36137 times.

As far as I know the FAA has not yet implemented the AAIB's recommendations in any ADs (or however they would do it). It would be interesting to know if UA has gone ahead and inerted ELTs on their 787s anyway.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: 777Boeing777
Posted 2013-07-19 08:36:25 and read 36109 times.

Quoting gators312 (Reply 23):
Could a lightning strike in flight to the ELT antenna have begun the thermal runaway of the battery inside the ELT?

I would think that the pilots would have noticed something like that if it had happened. Also, other a/c (747s and an A380) have been hit by lightning, and they've come out fine. I am pretty sure these a/c are built to deal with natural events (i.e. lightning) that are beyond its control.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: seahawk
Posted 2013-07-19 08:39:09 and read 36090 times.

Quoting Speedbored (Reply 49):
With the information available to me at present, I can't disagree with you or anyone else who says that it looks like there might be a systemic issue with the 787. But I'd also find it a bit difficult to disagree with anyone who claims the 787 is fine. I simply don't have enough information to be certain either way right now.

I would not discount the possibility of bad luck either. But then there is one connecting element. Lithium batteries in the 787 in aluminium casings. the previous events, where something I could easily agree with the idea, that a small fault in the battery design and a not satisfactory containment were good explanations and that there was no direct link to the rest of the aircraft. The new event forces me to reconsider. Again we got a thermal event form a Lithium battery in an aluminium casing in the 787, this time however a battery that is being used in the same application in huge numbers (Honeywell, Pointer ELTs for sure) in different aircraft, yet the first thermal event happened in a 787. Based on that I would say vibration is unlikely, unless there is a vibration frequency unique to the dreamliner. The only idea I could offer is the variable frequency starter generator.

This part at least has a connection to possible voltage spikes or missing electrical earth bonding. Both theories, I can imagine to be possible.

I tend towards condensation though, The reason is that the aluminium cases will probably change their temperature faster then the surrounding insulated CFRP panels. The ELT casing could easily be a cold spot inside the fuselage during cruise. (same as the old battery casing could have been cold spots after landing) So it might be that there is more condensation on the casing than in a normal fuselage, which is made of the same material. But that is pure speculation on my side.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Stitch
Posted 2013-07-19 08:41:14 and read 36143 times.

Quoting sphealey (Reply 47):
Here's a link that will lead you to the FAA's guidelines and training materials for fighting a lithium battery fire in the cabin. It is a matter of some concern to both the FAA and NTSB given the rapid growth of lithium chemistry devices over the last 5 years:
Quoting Finn350 (Reply 51):
It might be that end result of this investigation is to propose reverting back to Ni-Cd (Nickel-Cadmium) batteries instead of Lithium-Ion batteries in future applications (as Airbus already did with A350 primary & APU batteries).

Even before Boeing put in the new box, the cabin crew were not going to be fighting a fire in the Ship's or APU Batteries.  

The main danger of lithium batteries in the cabin are passenger devices and items like the ELT and emergency lighting (which use lithium batteries on at least the A380, A350 and 787 per reports).

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: 777Boeing777
Posted 2013-07-19 08:48:36 and read 35990 times.

Quoting flyglobal (Reply 28):

2) Humidity higher then all other planes before.

IIRC, the A380 has been touted as having similar, albeit slightly less than the 787, levels of humidity in flight.

Quoting flyglobal (Reply 28):
Special conditions at the day of incidence:
Very high otside temperatures
Probably humidity left when the plane was sent to parking position?

As an example, I live less than 5 minutes from IAD, and every morning around 6:30 am, SA207 arrives, and sits on a remote stand, exposed to direct sunlight, until it is towed to the terminal and then departs that evening at 1750. Summers are bad around here, but anyone in this area knows that for the last week we've been enduring a heat wave, with the heat index hitting ~105-110 degrees with +90% humidity. Not sure if the A343/346 has the same or similar device as the ET 787, but the environmental conditions are clearly worse.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: LTC8K6
Posted 2013-07-19 08:52:03 and read 35919 times.

Storage Temperature -40°C to 95°C

Anyone think it could have exceeded that in the 787 on that day? That is the storage temp range of the 5 cells presumably used in the ELT.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: 777Boeing777
Posted 2013-07-19 08:57:19 and read 35800 times.

Quoting LTC8K6 (Reply 68):
Storage Temperature -40°C to 95°C

Anyone think it could have exceeded that in the 787 on that day? That is the storage temp range of the 5 cells presumably used in the ELT.

95°C = 203°F. Highly doubtful the temperature would have come anywhere near that inside the 787.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Finn350
Posted 2013-07-19 08:59:00 and read 35772 times.

Quoting LTC8K6 (Reply 68):
Storage Temperature -40°C to 95°CAnyone think it could have exceeded that in the 787 on that day? That is the storage temp range of the 5 cells presumably used in the ELT.

General opinion here is that very unlikely, especially considering that the aircraft has passed successfully hot climate tests and this particular day & location is not extreme compared to what a plane typicall has to stand.

If thermal conditions are not the cause of the combustion, then based on the AAIB report a short-circuit (powered by the ELT battery) is next in the list.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: 777Boeing777
Posted 2013-07-19 09:05:26 and read 35714 times.

Quoting oldeuropean (Reply 43):
Don't mess with holders of Boeing shares, here on a.net.

At 106.42/share, mess with me all you want, because I would say the stock is doing just fine and I'm laughing all the way to the bank. Despite the ET incident, the share price rebounded the next trading day, and the stock has remained strong throughout the whole 787 saga.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: bikerthai
Posted 2013-07-19 09:37:29 and read 35190 times.

Quoting Speedbored (Reply 49):
3) Vibration.
And I'm not talking the sort of vibrations the aircraft manufacturers try to get rid of during flutter testing. I'm talking about the low level "humming" type vibrations caused by the engines or A/C power buses.

Vibration is another phenomenon that have been dealt with for decades. For the most part all LRU are design to airplane vibration spectrum defined through past experience. During flight testing these vibration spectrum are verified on the 787.

The individual supplier test their design on a shaker table (in operation mode) to verify that the LRU meet the requirement of the spectrum. Those boxes that can not meet the requirement on their own sometimes are mounted to a shock isolated tray. (Both box and tray are verified on the shaker table).

bt

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: spacecadet
Posted 2013-07-19 09:49:36 and read 34976 times.

Quoting hivue (Reply 55):
Many beliefs turn out to be worth nothing, but every well-reasoned, accepted scientific theory began life as a belief.

"Theorize, then test" is the scientific method. (Without a theory to start with, there'd be no way to ever prove anything.) Of course, most of us here don't have the ability to test, but we can certainly theorize and there's nothing wrong with that. Hopefully the AAIB are theorizing as well, and will then test the most promising theories to finally solve the puzzle.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: kanban
Posted 2013-07-19 10:10:45 and read 34698 times.

Quoting bikerthai (Reply 52):
These are general design practice in the industry and most likely would have been applied to this situation.

bt, exactly what I have witnessed in years of process inspections and reviewing process documentation. On the side we found sometimes that drainage paths got blocked with FOD ( both from regular assembly installation work but frequently for out of sequence work) or overzealous anti corrosion applications (paint and Dinol) these lead to problems.. further in delivered a/ps drainage paths got blocked around doorways, lavs and galleys through customer maintenance .. (sweeping instead of vacuuming)

Quoting bikerthai (Reply 53):
Grouding/Bonding - Static Discharge.

While everybody is talking about grounding, I wonder if the plane was grounded after being parked..   

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: BruceSmith
Posted 2013-07-19 10:28:23 and read 34463 times.

Quoting nm2582 (Reply 62):
For size comparison - The CR34610 is about the size of a common flashlight "D" cell battery (or at least that's the designation we use in USA - I'm not sure if different countries use a different designation). The CR123 is much smaller (and thus contains less energy).

After some digging through Duracell's site for their CR123 cell and the Ultralife site for the CR34610 cell, found the following.

The CR123 contains 0.55g of Li, and the CR34610 contains 3.33g Li. The battery for the Rescu 406 AFN unit contains 5 cells, which if they are the CR34610 cells, means 16.65g Li in the combined battery. A laptop battery pack of 6 cells is around 4.5g as best as Google can tell me.

If a battery with 4 times the lithium weight of an average laptop battery catches alight, there will definitely be enough heat to overcome fire-resistant materials. Just look at the laptop battery going off in http://www.youtube.com/watch?v=j4DlUUZxFvs for how much flame these things can produced.

Some contributors have discussed the electrical short mentioned in the AAIB release in terms of the external wiring of the ELT. The short could also be in the ELT itself, but outside of the battery pack, and still be responsible for the fire.

Lightning could strike the antenna and cause battery damage by over-voltage across the battery leads, but that should cause massive damage to the circuits of the ELT as it does so.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: hivue
Posted 2013-07-19 10:31:30 and read 34410 times.

Quoting kanban (Reply 74):
While everybody is talking about grounding, I wonder if the plane was grounded after being parked..

According to the AAIB the ground power cable was connected although the power was turned off.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: kanban
Posted 2013-07-19 10:40:42 and read 34542 times.

Quoting hivue (Reply 76):
According to the AAIB the ground power cable was connected although the power was turned off

good to know.. little ooops's like that can lead to trouble.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Speedbored
Posted 2013-07-19 10:46:49 and read 34491 times.

Quoting kanban (Reply 74):
While everybody is talking about grounding, I wonder if the plane was grounded after being parked..

I thought that aircraft have conductive tyres so that the ground themselves on landing. I believe that the tyres have a relatively high resistance so that they don't discharge any static charge too quickly.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: TheRedBaron
Posted 2013-07-19 10:52:15 and read 34414 times.

Quoting Speedbored (Reply 26):
Here's hoping I don't live to regret it.  

Great first post!!! good points! You wont regret it..welcome to the madness...

TRB

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: kanban
Posted 2013-07-19 10:57:08 and read 34337 times.

Quoting Speedbored (Reply 78):
I thought that aircraft have conductive tyres so that the ground themselves on landing. I believe that the tyres have a relatively high resistance so that they don't discharge any static charge too quickly.

nice to have you on the forum

while tires may provide a little grounding, some Boeing a/p's the landing gear is electrically isolated from the fuselage (737 nose gear for example), the primary method is via grounding studs on the plane to grounding studs in the tarmac.. some a/p studs are on the landing gear, others on the basic structure and others on the wing for use during fueling/de-fueling.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: B777fan
Posted 2013-07-19 11:19:04 and read 34004 times.

Quoting ZB052 (Reply 42):
Therefore i find your 'vent' a little hypocritical -

I think it's clear you missed his point.

He did not say that the ELT started the fire. He simply countered the unsupportable assertions that some have made that they can't believe an ELT battery could start a fire.

It is obvious to a knowledgable person that an ELT battery could start a fire. The fact that most batteries never start fires is irrelevant. The fact that 6000 ELT's of the same type are in use is irrelevant. While we don't know if or how it did start a fire, it is certainly possible.

I think that was the non-hypocritical reason for his venting. He sounded frustrated at having to sort through the drivel. More posts will likely still be made saying 'I don't believe the ELT battery could start the fire'. Those posts will be demonstrably false even it is proven that the ELT battery did not cause the fire.

By the way, theorizing that 'the ELT did not start the fire' is not equivalent to saying that 'the ELT could not start the fire.'

The second statement is absolutely false. The first is simply unknown and a plausible belief.

[Edited 2013-07-19 11:37:50]

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: nomadd22
Posted 2013-07-19 11:37:00 and read 33760 times.

Quoting LTC8K6 (Reply 31):
Why would there be high humidity when it's parked? The "high humidity" for pax is when the plane is flying, provided by the aircon system.

The "high humidity" in the 787 is something like 15% at a cabin altitude of 6K feet, just like the newest airbuses, iirc.

So it's hardly what you'd call high humidity, if you weren't in an airplane.

I'm not sure where you've been for the last 8 years, but the 787 structure allowing higher humidity has always been a major selling point. It's normally around 30%.
But, that probably wouldn't be the problem. The biggest chance of humidity causing trouble would be if the plane was left open to warm, moist air hitting a cooler ELT. In fact, being normally turned off until triggered is a bad thing when you're worried about humidity. The best way to protect from condensation is for the device to be a few degrees warmer than the surrounding air.
I'd think more about the lightning angle myself. After thirty-odd years of repairing lightning damage and figuring out how to prevent it, the main conclusion I've come to is that the only predictable things about lightning is it's unpredictability. I've seen it travel through whole systems without causing harm until it reached the point it decided to fry something. Not having the ELT grounded might be a really bad idea. Things that have just enough conductance to ground to be uncharged can draw lightning strikes, but not have a good path for the current.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Finn350
Posted 2013-07-19 11:43:36 and read 33611 times.

Quoting nomadd22 (Reply 82):
In fact, being normally turned off until triggered is a bad thing when you're worried about humidity

Speaking about the ETL being turned on, does anybody if those monthly 5-sec self-tests can be tracked? The ELT in question is basically off almost all the time (save a Real Time Clock I suppose), and turns on for a 5-sec self-test monthly to broadcast a test signal.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: LTC8K6
Posted 2013-07-19 11:50:18 and read 33522 times.

Quoting nomadd22 (Reply 82):
I'm not sure where you've been for the last 8 years, but the 787 structure allowing higher humidity has always been a major selling point. It's normally around 30%.

According to the info I could find on the net, the humdity in flight for earlier airliners is normally around 5% and the 787 increases that up to 15%.

Airbus gives a 20% figure for the A350, so it seems like the data for the 787 is probably correct.

"With the 787 fuselage made of composite material, it's possible to increase the humidity without corroding the airplane over time. On the 787, the manmade composite material is formed and baked into large barrels that are linked together to form the fuselage. The composite material doesn't corrode as aluminum does. As a result, the 787 cabin air system will allow 15% humidity, a more comfortable level than the current 4%."

http://usatoday30.usatoday.com/money...l/2006-10-30-boeing-air-usat_x.htm

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: LTC8K6
Posted 2013-07-19 11:54:31 and read 33451 times.

The problem with the condensation theory would be the length of time the plane was parked.

If it was condensation from the outside humid air hitting a cold ELT, one would expect the short circuit to have occurred relatively shortly after the plane was parked, not hours later, long after temps would have equalized and condensation should have evaporated..

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: LTC8K6
Posted 2013-07-19 11:58:09 and read 33467 times.

It would appear that the 787 and A350 both have systems to prevent condensation in the crown.

http://www.ctt.se/thezonaldryingsystem___215.aspx

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: WingedMigrator
Posted 2013-07-19 12:27:11 and read 32976 times.

Quoting LTC8K6 (Reply 85):
one would expect the short circuit to have occurred relatively shortly after the plane was parked, not hours later

This doesn't indicate anything one way or the other, since the fire could have smoldered unattended for hours before growing into a proper conflagration.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: sankaps
Posted 2013-07-19 12:31:41 and read 32950 times.

Quoting WingedMigrator (Reply 87):
the fire could have smoldered unattended for hours before growing into a proper conflagration.

A scary thought if this had happened mid-ocean, one would think.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: LTC8K6
Posted 2013-07-19 12:43:55 and read 32807 times.

Quoting WingedMigrator (Reply 87):

This doesn't indicate anything one way or the other, since the fire could have smoldered unattended for hours before growing into a proper conflagration.

Could be, but It doesn't seem likely to me. The batteries have a lot of energy and are inside a tough aluminum case. I think if they went off, it was impressive, not smoldering.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: LTC8K6
Posted 2013-07-19 13:42:03 and read 31952 times.

The AAIB report doesn't say there have never been thermal events with the 406AFN.

It says this was the only "signifcant" thermal event and that thermal events among the units are rare.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: JRenavitz
Posted 2013-07-19 13:48:49 and read 31852 times.

Quoting Speedbored (Reply 49):
It's no secret on Anet that Boeing might have made some mistakes on the outsourcing of the design and development of the electrical system. I get the impression that Boeing designed the system at a high level and then delegated the detailed design and development of individual parts of the system to many different contractors and subcontractors. I can't help wondering whether this might have led to the development that of lots of subsystems that work well in isolation but maybe have issues when interacting with one another.

I very much enjoy reading your posts. While I agree with your statement, I have to ask isn't this systems design 101? Again, not arguing your point, but questioning that if true it seems as an inexecusable violation of a fundamental principal - it's more important how the system works in its entirety compared to individual component/sub-syatem testing.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: uta999
Posted 2013-07-19 15:03:25 and read 30985 times.

I have a theory.

The 787 is made largely from composite material similar to plastic. This must generate a large amount of static electricity during flight, which is not grounded. This static charge could be starting fires hours after landing.

Could some of this static be getting inside the fuselage and into the wiring. All these battery events appear unique to the 787. It sounds like the Ni-Cad is being excited by an external charge, leading to heat and short circuit, even on batteries that are not rechargeable.

If you rub a balloon, static will stick it to a wall. Could the same science be happening to the hull of the 787?

This might explain the 787 unique run of bad luck with batteries, smoke and ultimately fire.

Does the 787 simply need grounding (for static) on arrival?

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Klaus
Posted 2013-07-19 15:08:12 and read 30838 times.

Quoting Stitch (Reply 20):
But based on the post of an employee of a 787 operator, it appears the ELT is not near any power conduits. So could such an event happen? Does anyone know the voltage and current of the wires that are connect the ELT to the cockpit?

I was considering the theory that a short circuit of an ELT control line with a power line might have injected external current into the ELT.

Yes, that is rather unlikely, but until the AAIB has checked the wiring and the ELT remains to the elimination of such scenarios, it is not impossible.

Quoting Speedbored (Reply 26):
Perhaps there was a fault in the flightdeck control panel or a data concentrator, or a short between a data cable and a nearby power cable or one of the many connectors somewhere en-route.

I doubt that the ELT control lines are mixed into a concentrator – that would seem illogical for a device of that purpose.

But the wires might be vulnerable. Even though (as I had remarked above already) the ELT interface circuitry should normally be hardened against such interference, which is quite feasible.

Quoting Stitch (Reply 20):
The condensation issue is an interesting one. Is the ELT installed underneath the fuselage or in a blister on top?

It's within the fuselage, apparently mounted to the structure from within, only the separate antenna extending to the outside.

Quoting Speedbored (Reply 49):
Given that the most recent event is different in a number of respects from the first two, it looks to me that the three fire or "fire-like" issues so far can just about be accommodated within the normal bounds of probability. Once-in-a-million-flight-hours doesn't have to mean that there will be a million event free hours before the first event, nor that there must be a million hours between the first and second events. Another event happening this year, however, might make the statisticians think twice.

When you start from the same baseline as with other aircraft, the previous fires were already highly significant statistically. Including this one the probability of all of them being accidental is probably vanishingly remote.

But the 787 does not have the same baseline as other aircraft, and some common causes have already been identified and fixed or at least mitigated for the most part.

It remains to be seen how that has shifted the statistical baseline now.

Quoting Speedbored (Reply 49):
In any electrical system with things regularly switching on and off, voltage spikes will be created by the switching, even when using solid-state switches. These spikes are usually smoothed out using accumulator devices such as capacitors or magnetic coils. As accumulator devices contain a lot of metal, they are heavy, so I can see why some of the subsystem developers might have taken the approach of "we'll assume that the signals and power that we get will be smooth" to keep the weight of their own sub-assemblies down. i.e. assume it's someone else's problem to smooth out the spikes. And, as Boeing only concerned themselves with the high level design, maybe they didn't pay much attention to this until it was too late. Or maybe any spikes they found during testing were insignificant enough to not cause damage. Perhaps the spikes only get sufficiently large to cause damage when a flap motor, a toilet flusher, an oven and a coffee pot all switch off at the same time. So perhaps it was the coffee pot's fault after all.

That is unfortunately a possible scenario connected to ill-conceived outsourcing.

Keeping the global design in mind even when considering detailed design decisions is a crucial function of technical project leadership.

And what you've described is one of the things that can get lost when work is split up without anybody retaining the global design responsibility.

This may or may not actually be the case – but it is a risk in Boeing's recent situation.

Quoting Speedbored (Reply 49):
3) Vibration.
And I'm not talking the sort of vibrations the aircraft manufacturers try to get rid of during flutter testing. I'm talking about the low level "humming" type vibrations caused by the engines or A/C power buses.

I have my doubts, however, whether a solid state device bolted to the fuselage will actually suffer from such vibrations without those vibrations at the same time being noticeable and annoying to the passengers. And that doesn't seem to be an issue.

Quoting hivue (Reply 55):
Many beliefs turn out to be worth nothing, but every well-reasoned, accepted scientific theory began life as a belief.

No, absolutely not!

A theory is an idea which you're explicitly subjecting to questioning and verification.

A belief is an idea that you have abandoned to question and verify.

The two are almost direct opposites.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: bikerthai
Posted 2013-07-19 15:14:50 and read 30736 times.

Quoting uta999 (Reply 92):
This must generate a large amount of static electricity during flight, which is not grounded. This static charge could be starting fires hours after landing.

The a metal aircraft in the air is also not grounded and can pick up static charge. They have static discharge probes on the wing trailing edge for discharging purposes.

The 787 static discharging system are the same.

bt

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Klaus
Posted 2013-07-19 15:25:18 and read 30563 times.

Quoting uta999 (Reply 92):
The 787 is made largely from composite material similar to plastic. This must generate a large amount of static electricity during flight, which is not grounded.

Not grounded to actual earth, but as far as I'm aware all systems share a common electrical ground, meaning there will not be any substantial potential difference between the fuselage and the internal electrical systems, even if the entire plane picks up a static charge – but that charge is relative to actual earth, not relative to the internal electrical system, which should be at the same charge potential so no discharge will happen internally.

And to the outside the above mentioned static wicks should softly dump the charge overboard in time.

Quoting uta999 (Reply 92):
Does the 787 simply need grounding (for static) on arrival?

The potential relative to earth is largely irrelevant, unless a charge transfer is actually taking place. The ET 787 was connected to a ground outlet, so it was actually connected to earth potential even while power was off.

Quoting uta999 (Reply 92):
Could some of this static be getting inside the fuselage and into the wiring. All these battery events appear unique to the 787. It sounds like the Ni-Cad is being excited by an external charge, leading to heat and short circuit, even on batteries that are not rechargeable.

No. Li-Ion batteries – particularly those with cobalt electrodes as in the 787 – have always been known to be somewhat unstable. Even just tiny manufacturing defects, overcharging or other influences can cause them to burn up violently. they are compact and light relative to their electrical capacity – that is why they are used in mobile devices. But using them as the main batteries in an airplane has always been a pretty substantial gamble by itself.

External issues only add to that, but the batteries by themselves are fully sufficient to explain the fires.

Do you remember the spate of laptop batteries going up in flames a few years ago? The presumed(!) cause was tiny impurities being introduced during manufacturing at a Sony plant. Yuasa may have suffered a similar problem with their batteries for Boeing, but it is not easy to determine with real certainty with that battery type.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Dalavia
Posted 2013-07-19 17:11:58 and read 29495 times.

Is it odd that no photos have been released of the interior of the damaged aircraft?

This is a genuine question as I do not know what is 'normal' in such situations. I have seen photos issued fairly quickly of other incidents, such as the 787 battery incidents, and I am personally surprised that no photos have been released of this incident.

Is it normal not to have photos by this time after an incident?

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: KELPkid
Posted 2013-07-19 17:51:07 and read 29318 times.

Quoting Dalavia (Reply 96):
Is it odd that no photos have been released of the interior of the damaged aircraft?

You have a very secretive investigative body (AAIB), combined with a very secretive airline (Ethiopian)...I would say that the chances are probably pretty good that the general public won't get to see it until its (hopefully) fixed!  

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: KELPkid
Posted 2013-07-19 17:55:39 and read 29300 times.

Quoting Finn350 (Reply 83):
Speaking about the ETL being turned on, does anybody if those monthly 5-sec self-tests can be tracked? The ELT in question is basically off almost all the time (save a Real Time Clock I suppose), and turns on for a 5-sec self-test monthly to broadcast a test signal.

Hmmm...the man might be onto something here...    I wonder if the unit did its self test around the time of the incident.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: CO953
Posted 2013-07-19 18:01:37 and read 29244 times.

Quoting nomadd22 (Reply 82):
I'd think more about the lightning angle myself. After thirty-odd years of repairing lightning damage and figuring out how to prevent it, the main conclusion I've come to is that the only predictable things about lightning is it's unpredictability. I've seen it travel through whole systems without causing harm until it reached the point it decided to fry something. Not having the ELT grounded might be a really bad idea. Things that have just enough conductance to ground to be uncharged can draw lightning strikes, but not have a good path for the current.

Lightning depends on a bunch of factors. I have witnessed quite a few lightning strikes, and been struck once, and have noted the unpredictability myself:

1. Boy-Scout camp in 1978, up in the mountains. I and others were 100 feet away from a 10-ft.-tall wooden tower being built by Scouts, anchored into earth by metal augers, and with a metal flagpole atop it. Happened to be looking that way and saw the sky open like a 3rd dimension and a giant crash that made us all fall on the ground. We got up and the tower was on fire and had to be put out.

2. Driving over a high metal bridge over low swampland at night in an '87 Toyota pickup, with cruise control on. Giant crash/flash as I cross under the first main metal arch....I am blinded and have to stop. Aftermarket, bolt-on cruise control box disconnects at moment of lightning strike and never works again.

3. Standing inside NAPA Auto Parts during lightning storm in 2007, car parked outside. Friend starts to walk outside and I tell him to stop due to lightning bolts. He turns around at the door and says, "what?" and lightning bolt hits large metal sign and I see it branch off and hit my car antenna 20 feet from the NAPA door. I get in the car and now the 8-track stereo won't work and there is a black burn mark on the antenna, still visible in 2013. Stereo begins working again 3 months later and now still works 6 years later, but intermittently fails for no reason for a couple weeks, then starts working again.

4. Running out to my car in a driving rain at a high school with another teacher in 2003, trying to beat a lightning storm. Both of us stupidly have opened our metal-spoke umbrellas. We each reach our cars at the exact same time. I step into the 4-inch puddle of water beside my driver's door and reach out for the metal door handle. Giant crash and flash - I actually see a giant arc of electricity reaching out from the heavy, metal I-beam school marquee 25 feet away. It hits the top of my umbrella and I feel like a giant rubber band just hit me in the side of the neck so hard that I almost pass out and I feel like my brain skips for a few seconds like my balance is gone. I begin cursing, and at the same moment, I hear my friend, a devout churchgoer, curse, too. He got hit as well and I knew it because he doesn't curse. My arm shakes for about 1/2 hour afterward and I have some heart palpitations for an hour or two - but I'm OK. I am left wondering what would have happened had I grabbed the metal door handle 1/2 second earlier with my feet in the puddle.

Lighting strikes and CFRP fuselages now intrigue me. I wonder when the fire was ignited?

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: CO953
Posted 2013-07-19 18:07:17 and read 29213 times.

Just a random thought.... as fuselages create static electricity, could the location of the ELT antenna just forward of the vertical stabilizer be significant? Would the v. stab generate excess static electricity, due to its knifing action through the air, and if so could we be dealing with a static field that either amplified by a strike or by itself somehow got to the ELT circuit due to proximity?

[Edited 2013-07-19 18:08:30]

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: braynfeeble
Posted 2013-07-19 18:38:41 and read 29124 times.

Is ET-AOP DBER? Or what? Seems like most salvagable other than one portion.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: aklrno
Posted 2013-07-19 19:20:07 and read 29205 times.

Quoting CO953 (Reply 99):
3. Standing inside NAPA Auto Parts during lightning storm in 2007, car parked outside. Friend starts to walk outside and I tell him to stop due to lightning bolts. He turns around at the door and says, "what?" and lightning bolt hits large metal sign and I see it branch off and hit my car antenna 20 feet from the NAPA door. I get in the car and now the 8-track stereo won't work and there is a black burn mark on the antenna, still visible in 2013. Stereo begins working again 3 months later and now still works 6 years later, but intermittently fails for no reason for a couple weeks, then starts working again.

I got stuck reading your post when you said you had an 8-track in 2007. Can't get any farther.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: YVRLTN
Posted 2013-07-19 20:39:09 and read 28905 times.

Quoting Speedbored (Reply 30):
Composite instead of metal? That's one area where I think there could be issues. Previous metal aircraft have relied on the aircraft structure to provide a common earth for the electrics and electronics. Obviously, this isn't possible with non-conducting composite, which is why Boeing have added a metal mesh to the structure. I can't help wondering whether something went wrong with the earthing of the ELT

Thanks for your posts. I mentioned earthing in a previous thread and the discussion came to an end as it was locked and the discussion moved on before I could ask more questions of RCAir in particular. My understanding is the potential earthing problem unique to the 787 is actually more "internally" generated than externally by static. From what I understand of an investigation done by senior electricians at Boeing into the previous battery issues, you pretty much nail it with all three of these below - I can see how similar could apply to the ELT battery too.

Quoting Speedbored (Reply 49):
1) Electrical Earth Bonding.
Quoting Speedbored (Reply 49):
2) Voltage spikes.
Quoting Speedbored (Reply 49):
3) Vibration.

Vibration normally would not be an problem, but say there was another issue with a faulty component for example a manufacturing defect even by micro units of measure and the wiring connections were not sealed properly - lets say a connector in the wiring of the battery (of the ELT or the main batteries) to the rest of the system which of course enables current incl voltage spikes / arcs to directly pass through the steel protection boxes via wires to the battery (or does it? I would like to think there is some sort of protection here). Normal vibrations of an airframe would only excaberate such an issue (ie a simple loose wire) and maybe would cause your other two issues too?

Quoting Speedbored (Reply 49):
I get the impression that Boeing designed the system at a high level and then delegated the detailed design and development of individual parts of the system to many different contractors and subcontractors. I can't help wondering whether this might have led to the development that of lots of subsystems that work well in isolation but maybe have issues when interacting with one another

Maybe a sub supplier changed the agreed spec from Boeing by a miniscule amount that they were unaware of? So when it came to application by Boeing on the FAL they have an unknown unkown. Of course it take the holes of the cheese to line up as with many mysterious incidents, but this could only become a problem when connected to something highly volatile in make up - ie a battery and the rest of the time the energy is dissipated in the designed way.

So dodgy connector => loose wire => uncontained current / voltage spikes / arcing exacerbated by vibrations => fire at point of most flammable / volatile terminus of said current.

As Im not a sparky, I dont quite get how this would happen with the aircraft powered down on stand, though it was plugged in to ground power. Rather than bashing as impossible, I would appreciate thoughts, particularly from our newest member.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: B777fan
Posted 2013-07-19 22:14:39 and read 28528 times.

Quoting LTC8K6 (Reply 85):
If it was condensation from the outside humid air hitting a cold ELT

Rain in the plane, is condensation that builds up in flight on the cold inner surface of the hull and then freezes. It later melts and can pool, drip or run along wires.

The water has already accumulated by the time the plane is parked and it may not evaporate if it has pooled.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Finn350
Posted 2013-07-19 22:34:09 and read 28541 times.

It looks like a pinched wire inside the ELT casing and condensation in the crown area might be to blame based on this Reuters article. If this is accurate, this time the root cause will be found quite quickly. There might be other ELTs in other planes around with a pinched wire but 787 is unique having higher humidity levels.

"Exclusive - Boeing 787 probe looks at condensation, wiring"
http://uk.reuters.com/article/2013/0...nvestigation-idUKBRE96I18520130720

[Edited 2013-07-19 22:35:10]

[Edited 2013-07-19 22:54:06]

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: flyglobal
Posted 2013-07-19 23:40:37 and read 28164 times.

Quoting Finn350 (Reply 107):
t looks like a pinched wire inside the ELT casing and condensation in the crown area might be to blame based on this Reuters article. If this is accurate, this time the root cause will be found quite quickly. There might be other ELTs in other planes around with a pinched wire but 787 is unique having higher humidity levels.

"Exclusive - Boeing 787 probe looks at condensation, wiring"
http://uk.reuters.com/article/2013/0...30720

Sounds plausible to me.
My engineering brain is not surprized, as I expected something related to the built in condition in the 787 rather then the component itself or just bad luck.

Probably Boeing has to overhaul the 787 belectric system. An electric PIP.

Should probably come to production with the 789.

regards
Flyglobal

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: CO953
Posted 2013-07-19 23:45:26 and read 28159 times.

Quoting aklrno (Reply 103):
I got stuck reading your post when you said you had an 8-track in 2007. Can't get any farther.

I fly old metal  

Sorry for the whiplash..

Quadraphonic, no less, in 2013

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: JoeCanuck
Posted 2013-07-20 02:02:15 and read 27657 times.

I call BS on the condensation theory specific to the 787. For one thing, a composite skin is more thermally insulative than a metal one, so condensation is less likely to collect against the skin. 15% humidity, while more than most metal skinned planes, (except for the 380, I believe), is almost nothing.

We're talking about a manufacturing fault on the ELT. Since it's supposed to be waterproof, (which it seems it wasn't), it's hardly the fault of the plane that moisture got inside. Not only that, it seems another ELT manufacturing fault created the conditions where water could have caused a short.

Most of the electronics including radios, flight instruments and basically everything electronic in the cabin, is open to atmosphere, (for cooling if nothing else), and if humidity was an issue for electronics, aircraft parked in high humidity locations would be sparking like fireworks. Anybody who has flown from a high humidity location, (DXB is a good example), fog from the A/C filling the cabin is a regular event.

The ELT battery is supposed to be sealed within the device, completely isolated from the electrical system of the aircraft...except for an arming switch in the cockpit...and there's not enough voltage or current from the switch to create a spark, much less start a fire.

The 777, 380, 330 and other aircraft have electronics in unpressured parts of the aircraft which don't have any protection from temperature or humidity and they're doing just fine.

If it was the ELT,, it wasn't a 787 specific outsourcing issue since nobody makes their own ELTs. They are always outsourced.

There is still no final report and maybe the CFRP did have something to do with the fire....but if it's the ELT, pinning this on Boeing will be one heck of a stretch.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: seahawk
Posted 2013-07-20 02:21:26 and read 27499 times.

Quoting JoeCanuck (Reply 108):
I call BS on the condensation theory specific to the 787. For one thing, a composite skin is more thermally insulative than a metal one, so condensation is less likely to collect against the skin. 15% humidity, while more than most metal skinned planes, (except for the 380, I believe), is almost nothing.

Interestingly all those batteries were inside aluminium cases, when they had a thermal event. So maybe those battery cases did get more condensation than usual, not only because of the higher humidity but also because the normal fuselage is better insulated, maybe creating more water on those metal cold spots.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: zeke
Posted 2013-07-20 02:31:00 and read 27486 times.

Quoting JoeCanuck (Reply 108):
15% humidity, while more than most metal skinned planes, (except for the 380, I believe), is almost nothing.

I would expect atmospheric humidity in an aircraft that had been sitting on the ground for a while after flight, and then the cabin doors closed. The temperature in London around that time was hitting around 30 deg C.

Quoting JoeCanuck (Reply 108):
The 777, 380, 330 and other aircraft have electronics in unpressured parts of the aircraft which don't have any protection from temperature or humidity and they're doing just fine.

What are you thinking of ? the items that I am familiar with all are housed in environmentally protected housings, e.g landing gear computers, fuel computers, flight controls, Wx radar etc.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: mjoelnir
Posted 2013-07-20 03:56:41 and read 27071 times.

Quoting JoeCanuck (Reply 108):
There is still no final report and maybe the CFRP did have something to do with the fire....but if it's the ELT, pinning this on Boeing will be one heck of a stretch.

Here is some strange reasoning.

If the culprit is the ELT, than unless the ELT is a user supplied item, it is still Boeings responsibility.

It is strange how convoluted the arguments get to absolve Boeing.
Boeing is a great producer of outstanding airplanes, but a manufacturer is responsible for the stuff he puts on his equipment.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: garpd
Posted 2013-07-20 04:27:25 and read 26877 times.

Quoting mjoelnir (Reply 111):
It is strange how convoluted the arguments get to absolve Boeing.

It is also strange how convoluted arguments get to blame Boeing. In your very own post for example.

The ELT is a customer option. It is certified for use on commercial aircraft and has been in use for quite some time. It is delivered to Boeing from Honeywell and installed into the aircraft during assembly.
Much the same as the engines on the wing. Order and bought by the customer, delivered to Boeing and installed on the aircraft during assembly

So, we have two components, not built by Boeing, certified and test for use. Installed by Boeing on a new Aircraft.

If an engine were to fail, say puncture a large hole in the wing and cause an emergency and safe landing in say, oh... Singapore. Who is responsible? Yes, the engine manufacturer.

I do believe that when the Qantas A380 suffered such an episode, everyone here blamed RR. And rightly so. There was not a shadow of doubt on Airbus or the A380. Quite correct. This is logical. The engine was made and tested by RR before being installed on the aircraft. It then passed flight testing and flew quite well up until its failure. Airbus could have done nothing to prevent it.

Now, all of a sudden, because the subject is the 787, this logic thrown out.
A failure of a non Boeing item* can only be Boeing's fault? Seriously? And people are stipulating this before a final report is out telling us exactly what cause the fire and how. Yet it is still assumed to be fair and logical to pin this on Boeing.

And don't come back with a "well, there were 2 other battery fires before, so if the shoe fits, etc. Those two batteries and those in the ELT have absolutely nothing to do with one another. They are not connected in any way to each other. The only common factor is they are aboard a 787. That in itself is not permissible as evidence of guilt.

I'm not saying Boeing IS innocent here. I've not made any judgement myself yet as the investigation is yet to conclude, present it's findings and evidence thereof.
I find it therefore premature and highly questionable of anyone to suppose guilt on any party ond way or the other at this stage. The fact the 787 had previous problems is irrelevant until such time the investigation finds hard evidence of a link to any previous issue. But until such time, this incident, IMO and I'm sure that of the AAIB's also, this fire should be treated as unique and independent event.

* Assuming for the sake of argument, the ELT and it's battery are announced as the reason

[Edited 2013-07-20 04:28:52]

[Edited 2013-07-20 04:31:06]

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Tristarsteve
Posted 2013-07-20 04:47:59 and read 26754 times.

Quoting mjoelnir (Reply 111):
A failure of a non Boeing item* can only be Boeing's fault? Seriously?

So when is a part a Boeing part?
Centre wing box? made in Japan?
Wings?
Undercarriage?
Windscreens?
Rudder?
All made by subcontractors. What parts does Boeing make that they are responsible for?

Quoting garpd (Reply 112):
The ELT is a customer option

But you can only choose to have it or not, there is no choice of design.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: AirlineCritic
Posted 2013-07-20 05:07:18 and read 26618 times.

When looking for possible other causes, please remember that aircraft such as the 787 are complex objects. There is a lot of new technology and new ways of doing things in there. Not just CFRP and non-bleed based design that have been widely touted in the public, but many other things. There could be new approaches in systems. Wires. Cabin construction. Insulation. Power distribution architecture. And many other things that we don't get to know.

Based on the amount of lithium in the ELT battery, I find it easy to believe it could start a fire. I find it less easy to understand how the fire spread. How fire resistant are, e.g., wiring and insulation expected to be in aircraft? The ELT battery can start a fire, but I do not believe it would be enough for the kind of damage seen on the hull. So what would be the fuel for the rest of the fire? Or would the energy in the ELT battery be enough light the CFRP itself in fire, in one specific location, and then letting the fire spread from there? Seems unlikely, but...

Quoting Speedbored (Reply 26):

Welcome to a.net as a poster! Your contributions are appreciated.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: dynamicsguy
Posted 2013-07-20 05:12:08 and read 26603 times.

Quoting Speedbored (Reply 49):
I then got wondering about the difference between aluminium and CFRP in terms of absorption of low level vibrations. My guess is that metal, being softer, will absorb more of the vibrations than CFRP which, being more rigid, probably passes on the vibrations to be absorbed by softer materials elsewhere like seat cushions, bodies or battery electrolyte, perhaps?

Generally speaking, composite materials are inherently better damped than aluminium, so will damp out any vibration better. On the stiffness part of the equation it's hard to say one way or the other as it's dependent more on the structural design.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: LTC8K6
Posted 2013-07-20 05:14:15 and read 26620 times.

Quoting B777fan (Reply 104):

Rain in the plane, is condensation that builds up in flight on the cold inner surface of the hull and then freezes. It later melts and can pool, drip or run along wires.

The water has already accumulated by the time the plane is parked and it may not evaporate if it has pooled.

Again, the 787 has, as standard equipment, a system from CTT to reduce humidity in the crown, so I would think it odd to have that phenomenon on the 787.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: LTC8K6
Posted 2013-07-20 05:17:57 and read 26649 times.

The Zonal Drying™ System

The leading method for preventing excess moisture.

The Zonal Drying™ System prevents condensation in modern aircraft by combating the root cause. Less condensation means less weight resulting in lower fuel consumption and emissions.

The system effectively removes moisture using established industrial technology. The system takes air from the crown area or cargo area and feeds it though zonal dryer units between the cabin and the outer skin of the aircraft using a specially designed piccolo duct. This lowers the dew point in the crown area preventing the condensation process from occurring, thus keeping the insulation blankets dry.

Depending on aircraft type, the Zonal Drying™ System consists of one or more zonal dryer units installed at strategic points in the aircraft. Each unit features a slow-moving rotor impregnated with silica gel.

The Zonal Drying™ System is standard equipment on Boeing 787 "Dreamliner" and furthermore available as BFE option on Boeing 737NG.

http://www.ctt.se/thezonaldryingsystem___215.aspx

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: mjoelnir
Posted 2013-07-20 06:37:07 and read 26249 times.

Quoting garpd (Reply 112):

I run my own company.

It is very simple, I sell equipment, I am responsible for the stuff I supply with it. It is really that very simple. When I let my customer chose some things I supply out of a list, I am still responsible for it. Otherwise I have to tell my customer that I will not supply this parts and he has to buy and install it himself and I better put it down on paper that I do not approve or recommend it.

I can hop and jump and scream that somebody else produced some of what I supplied, but I will still be responsible for it.
I can than make my supplier responsible, but that is really another point.

The situation is rather worse when you get to aeroplanes. Everything is certified in regards to the type. Even if a part is certified to go on a A 330, A 340, B 777, it has to be certified again going on a B 787, and the air framer is responsible.

Really simple, very simple.

And if you compare the A 380 from Qantas, Airbus does not sell the engines to Qantas, RR does it in a separate deal.
But even than Airbus chose the engine and had it certified on the A 380 and shares in the blame.

As I understand it about 70% of the B 787 is not produced by Boeing, were do you want to draw the line of no responsibility?
Electrical brakes? Flight computers? Main landing gear? All that is supplied by somebody, all that is the responsibility of Boeing.

A defect part chosen by Boeing for the B 787, even if it is optional, is the responsibility of Boeing.
Boeing can than fight it out with his supplier.

P.S. Even if it is really the ELT it can still be a installation problem rather than a defect in the ELT itself. But that does not matter regarding the responsibility.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: kanban
Posted 2013-07-20 09:08:49 and read 25573 times.

To understand Buyer Furnished Equipment,
* the customer buys it and transfers the item or purchase order to Boeing to ensue timely arrival for installation.
* Boeing engineers look at fit and function, and design the necessary attach and control points and perimeters if required..
* On arrival at the Boeing site for installation, they are inspected only for shipping damage
* On installation they are only inspected to the installation plan/drawing and any functional test required to ensure (as in this case) the controls are working.
* If a unit is bought by the customer and installed by the customer after delivery, Boeing's effort ends with ensuring the attach points match the customer requirement. (ie BA seats)
* Since Boeing is neither the designer, manufacturer, nor test no contracting body, but merely a processor for the customer, they are only accountable for the interfaces and ensuring the item is free of shipping/installation damage and simple tests to ensure control linkages work. In this case, it appears that there appears to be a pinched wire internally.. something that would not have been noticed when looking for shipping damage because they do not open sealed units especially since they are not an authorized repair station.

The difference with the Boeing designed and purchased components and sections is Boeing designs (or contracts the design), approves the design, reviews and approves the manufacturing facility, process, inspection and is fully accountable for all aspects. Boeing additionally is responsible for initiating and/or approving design and manufacturing changes.. Boeing has no authority in BFE design, manufacture or test. The only common authority is the FAA.

Now say you were buying a new car and asked the dealer to put a different tire on it (say a more aggressive tread) that the dealer does not stock but but can procure, if that tire has a manufacturing flaw that causes a blowout after a year, is the dealer responsible? Say your model came without GPS and you received one from your grandkids and installed it. Then you're driving along and it indicates a road intersection that doesn't exist and you drive off the road (believe me there are more than a few cases of people believing the GPS and not their eyes.), is the dealer responsible? after all they provided an electrical socket you plugged it into.

Now Lawyers will go after the big bucks regardless of involvement, and generally get spalled down.. some own here arguments here sound that way.. Maybe the fault lies with Heathrow not monitoring parked planes more rigorously. Maybe the countries adding carbon to the atmosphere that cause elevated temperatures are to blame..

However, if in fact it is a pinched wire and a thermal run away in a sealed piece of BFE, then it is the BFE manufacturer's problem, not the company that maybe moved too fast to bring new technology into production where some aficionados are still lamenting open cockpits, wooden structures and linen covered control surfaces.

Now some will argue I'm a Boeing retiree and fan boy... however I can be as critical of them as the next.. it's just knowing the processes involved, I don't criticize or whitewash with a wide brush like some. I use one wide enough to address the true responsibility.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: ncfc99
Posted 2013-07-20 09:36:41 and read 25380 times.

Quoting kanban (Reply 119):
In this case, it appears that there appears to be a pinched wire internally..

I haven't read the AAIB report but I have read exerts and various post on here and twitter etc. IIRC, the AAIB are recomending, amongst other things, to check for a pinched wire. I assumed this would be external to the ELT (between it and the cockpit) and the possible point of some arching that would cause the ELT to combust. If the ELT is a sealed unit, they can't check inside for pinched wires. Is my understanding correct or incorrect?

Quoting kanban (Reply 119):
To understand Buyer Furnished Equipment,

Again, as i've understood it, the ELT is an customer option, not a buyer furnished equipment. To my mind the later is seats, engines etc. They are negotiated, bought and paid for in a seperate deal from the airframe. An ELT is ordered, fitted and paid for with Boeing. Again, please correct me if I am wrong.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: multimark
Posted 2013-07-20 09:52:09 and read 25288 times.

Quoting garpd (Reply 112):
The ELT is a customer option. It is certified for use on commercial aircraft and has been in use for quite some time. It is delivered to Boeing from Honeywell and installed into the aircraft during assembly.
Much the same as the engines on the wing. Order and bought by the customer, delivered to Boeing and installed on the aircraft during assembly

So, we have two components, not built by Boeing, certified and test for use. Installed by Boeing on a new Aircraft.

Is this ELT an off the shelf model? If so, why hasn't the same issue arisen on other a/c?

And if it's built specifically for the 787 presumably Boeing supplied the specs.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: kanban
Posted 2013-07-20 10:03:03 and read 25229 times.

Quoting ncfc99 (Reply 120):
If the ELT is a sealed unit, they can't check inside for pinched wires. Is my understanding correct or incorrect?

the impression I have is the wire was inside the unit

Quoting ncfc99 (Reply 120):
Again, as i've understood it, the ELT is an customer option,

Customer options of this type are traditionally BFE

Quoting multimark (Reply 121):
And if it's built specifically for the 787 presumably Boeing supplied the specs.

I think we can conclude if there were several thousands of these units in use, that it was not designed specifically for the 787..

of course with some of the hysteria, if a operator added piece of equipment, like a demonstration seat belt piece fell out of a overhead storage when opened, it would be the CFRP's fault.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: JoeCanuck
Posted 2013-07-20 10:43:40 and read 25034 times.

Quoting zeke (Reply 110):

I doubt all of the individual componants or the bays are hermetically sealed. The electronics in the 787 battery bay are on open shelves...most are probably air cooled, and that air is likely shared with the cabin. I doubt they are designed or installed so they can survive being submerged, unlike the ELTs.

There are probably a lot of open connections behind the radio stacks and instrument panel. Open to the environment isn't the same as open to all of the elements. Their componants are subject to the same humidity as the rest of the cabin.

Quoting mjoelnir (Reply 111):

I'm not absolving Boeing of anything but the fact is, Boeing doesn't make ELTs...never has and probably never will. Neither does Airbus or any other aircraft maker. The ELT is very likely an off the shelf unit since all ELTs share the same function and have about the same specs.

An ELT for a 787 isn't very different than an ELT for a Cessna 172....and could very well be the same model.

These ELTs will have been certified by Honeywell for use in the 787 as they were designed to be installed and it's unlikely Boeing tests each one to see if they leak.....again...neither does any aircraft maker.

So if you can explain how Boeing should have known that the ELT had a crimped wire inside of a sealed container, have at it. Boeing will probably get the bill for it but they'll pass it along to Honeywell.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: kanban
Posted 2013-07-20 11:11:24 and read 24831 times.

the trade off with all the 'should have/could have' scenarios is: at what cost to the user and flyer. I recognize that those who fly on the company bill, however there are economics in building just as there is the sacred CSM.. 100% detail and assembly inspection of previously inspected items would make even the cost business flying out of the question.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: sassiciai
Posted 2013-07-20 11:44:41 and read 24675 times.

Tons of speculation, little fact! It's the British Open Golf right now (day 3 of 4) with Tiger Woods favorite to win, and the Ashes cricket between England and Australia (also day 3 (of 5)). Tour de France nearing its climax too!

I'd love to return to this thread when there was some more factual stuff to debate, but for now, I'll watch the golf! Come join me!

(I suspect moderator deletion of this post will happen quite soon as being off topic!). Only alternative to me is to stop reading the threads until more facts come to light! But I just find all the incessant speculative posts going round in circles in a factual vacuum a bit tedious! Sorry! 100 of them, OK! 1500 of them, no!

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: wingman
Posted 2013-07-20 12:01:22 and read 24610 times.

Quoting mjoelnir (Reply 111):
It is strange how convoluted the arguments get to absolve Boeing.
Boeing is a great producer of outstanding airplanes, but a manufacturer is responsible for the stuff he puts on his equipment.

I assume you are on record assigning blame exclusively to EADS for the deaths of 200+ people in AF447.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: mjoelnir
Posted 2013-07-20 12:48:52 and read 24527 times.

Quoting kanban (Reply 119):

The problem is just that the ELT is not a buyer furnished equipment. It is a option fitted by Boeing. It is bought from Boeing.

If you can show me that the buyer of the airplane buys the ELT, supplies it to Boeing and Boeing installs it I understand your post.
Even than Boeing has some responsibility.

To be a BFE the airline has to buy it not through Boeing and let Boeing install it. Even than it is equipment certified for the type of airplane and Boeing is involved in that as for example the engines.

If you buy your car and some of the optional equipment like heated seats burn your car it stays the responsibility of the manufacturer you bought your car off.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: francoflier
Posted 2013-07-20 12:53:07 and read 24540 times.

Quoting wingman (Reply 126):
I assume you are on record assigning blame exclusively to EADS for the deaths of 200+ people in AF447.

What?
AF447 - Pilot error, exacerbated by instrument failure (and yes, I would say EADS is fully responsible for not ensuring non freeze prone pitot tubes were installed)

On the other hand, I have a hard time seeing how the incident at LHR could be blamed on anything else than the machine, barring unlawful human interference...

On the account of 'responsibility' which crops up on here everytime anything happens, nothing could be simpler: follow the money.
Whoever ET paid for their spontaneous combusting airplane are the responsible party, the same way I'm heading straight to my friendly dealership when the electric windows fail in my car under warranty, even though they didn't build those... It's the same for any industry.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: airtechy
Posted 2013-07-20 13:10:48 and read 24404 times.

My take on the ELT matter is:

1: The ELT is not a custom design and is not an installation unique to the 787. For all we know it could be used on the A350.

2. If the ELT had an internal short that did not manifest itself during Honeywell test or incoming Boeing test, Boeing will be ultimately responsible and the lawyers will hash out the distribution of costs to repair the airplane. Honeywell will improve the build process.

3. If Boeing damaged the wiring installing the ELT, they will repair the plane and update the install procedure to prevent future problems or redesign the wiring.....engineering change....so that normal install procedures will not damage it.

4. We will all move on until the next 1000+ post thread caused by a normal "introduction into service" problem.  

AT

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Klaus
Posted 2013-07-20 13:21:58 and read 24349 times.

Quoting francoflier (Reply 128):
(and yes, I would say EADS is fully responsible for not ensuring non freeze prone pitot tubes were installed)

Those were selected not by Airbus, but by Air France. And "freeze prone" is a bit misleading – all pitot tubes can freeze under adverse conditions – and the ones on AF447 indeed froze under adverse conditions, but even so only temporarily.

The difference to other available models is as far as I'm aware not in those never, ever freezing at all but in freezing only for a shorter while and maybe less often. And pilots should expect that to happen under circumstances like those and be able to cope with it, instead of near-immediately losing control of the aircraft and losing track of the situation.

Where the limits of acceptable capability for such parts ultimately are can be debatable. But claiming that Airbus had a definitive part of the blame seems a bit overdone.

Quoting airtechy (Reply 129):
4. We will all move on until the next 1000+ post thread caused by a normal "introduction into service" problem.

Since when is severe fire damage to the point of a writeoff being debated on a high-ETOPS aircraft a "normal introduction into service problem"? What have I missed on other introductions?

It's actually not even clear whether it has really anything to do with the 787 at all, but if it does, it's more than just a slight hiccup.

[Edited 2013-07-20 13:29:18]

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: TC957
Posted 2013-07-20 13:30:42 and read 24307 times.

I don't know how significant this may be but ET-AOP got moved today from outside the old BMI hanger where she was taken to for examination to a stand over in the DHL cargo area.
I was at LHR today and where it was before being moved you could get quite close up behind her, the burn marks in front of the tail are there for all to see.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: trex8
Posted 2013-07-20 13:35:02 and read 24269 times.

The A330 pitot tubes met all certification requirents. The fact these turned out to be inadequate in service is hardly the manufacturers fault.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: PlanesNTrains
Posted 2013-07-20 14:03:45 and read 24095 times.

Quoting trex8 (Reply 132):
The A330 pitot tubes met all certification requirents. The fact these turned out to be inadequate in service is hardly the manufacturers fault.

The 787 ELTs met all certification requirements. The fact these turned out to be inadequate in service is hardly the manufacturers fault.

Glad we're all on the same page now.  

-Dave

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: jumpjets
Posted 2013-07-20 14:21:34 and read 23955 times.

Quoting TC957 (Reply 131):
I don't know how significant this may be but ET-AOP got moved today from outside the old BMI hanger where she was taken to for examination to a stand over in the DHL cargo area.

Perhaps she's going to be parcelled up and flown home using DHL urgent delivery services.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Speedbored
Posted 2013-07-20 14:33:09 and read 23953 times.

Quoting sassiciai (Reply 125):
It's the British Open Golf right now (day 3 of 4) with Tiger Woods favorite to win, and the Ashes cricket between England and Australia (also day 3 (of 5)). Tour de France nearing its climax too!

Fortunately, the Brits seem to currently be in the lead in all three of those events, which is a bit of a surprise.   

Quoting sassiciai (Reply 125):
Tons of speculation, little fact!

Unfortunately, while the Brits remain in the lead on this accident investigation, I think we're going to continue to suffer from a lack of factual information and continue with a surplus of speculation until at least an interim report is released.

But that's a large part of what this site is about. I for one have learnt a lot from the speculation that goes on on here, especially when it's debunked by explanations from people in the know. Long may it continue.

Quoting trex8 (Reply 132):
The A330 pitot tubes met all certification requirents. The fact these turned out to be inadequate in service is hardly the manufacturers fault.

Correct. If anything the blame lies with EASA, or whichever group agreed the certification standards which seem to have proved to be inadequate for the weather that AF447 encountered.

Quoting PlanesNTrains (Reply 133):
The 787 ELTs met all certification requirements.

Agreed.

Quoting PlanesNTrains (Reply 133):
The fact these turned out to be inadequate in service is hardly the manufacturers fault.

I'm not sure that it's the certification standard that was inadequate. Assuming that the fault was actually with the ELT, my money would be on the manufacturing (or quality control) or installation of it being the inadequate bit.

Quoting jumpjets (Reply 135):
Perhaps she's going to be parcelled up and flown home using DHL urgent delivery services.

  
That's going to require an awfully large amount of parcel tape and brown paper.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: rwessel
Posted 2013-07-20 14:55:33 and read 23743 times.

Quoting trex8 (Reply 132):
The A330 pitot tubes met all certification requirents. The fact these turned out to be inadequate in service is hardly the manufacturers fault.

Merely meeting the certification requirement should not be sufficient to absolve the manufacturer.

The Titanic's lifeboat complement met the certification* requirements. That the certification requirements were inadequate was blinding obvious (fewer seats in the lifeboats than butts on the boat).

Things are different, of course, if it's reasonable to believe that the certifications requirements *are* adequate.


*At the time, the regulations were written to specify the lifeboat requirements based on the size and capacity of the ship. The categories, as written, adequately covered the largest ships in existence at the time of writing, but they had not been updated. Ships were growing rapidly, and the Titanic was considerably larger than the largest ships covered in the regs, which required that ships of 10,000 tons or more carry lifeboats for 990 people. Titanic, of course, displaced 53,000 tons and carried 3300+ people. In fact, the White Star Line actually had more lifeboat capacity installed than the regs required (seats for some 1178), although obviously nowhere near enough.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: NeutronStar73
Posted 2013-07-20 15:00:59 and read 23760 times.

Quoting 777Boeing777 (Reply 60):

The problem is that this AAIB report, no matter how detailed and what they requested of the FAA (disconnect of 787 ELTs), all the members of the Boeing Bash Brigade (closely aligned with the Armchair Airbus Afficionado Squadron) will NOT accept any fact that will not support their narrative that Boeing makes bad airplanes.

I, like you, have gone elsewhere to get good information because there are precious few of those people who post here providing good info and enlightening posts. The 787 has been the subject of endless threads on A.net for some serious and not so serious issues, yet the website blows them up and we have 6 (and likely more, no matter what the AAIB report says) threads where the drumbeat will be the same: I don't care what the AAIB says, the 787 is crap, the batteries make it an unsafe airplane, it should be permanently grounded, and on and on.

AAIB says it's the ELTs (even asked the FAA to recommend a disconnect so an AD can be investigated and issued) and people will continue to say "NOPE! It's a fundamental flaw with the 787 and no amount of careful investigation
will change their minds.

Quoting garpd (Reply 112):
I do believe that when the Qantas A380 suffered such an episode, everyone here blamed RR. And rightly so. There was not a shadow of doubt on Airbus or the A380. Quite correct. This is logical. The engine was made and tested by RR before being installed on the aircraft. It then passed flight testing and flew quite well up until its failure. Airbus could have done nothing to prevent it.

Absolutely correct and as you, subsequently state, when it comes to Boeing, that logic is discarded completely. I think the thread should have ended with your very logical, unbiased post. Thanks you.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: sankaps
Posted 2013-07-20 15:20:50 and read 23671 times.

Quoting kanban (Reply 119):
To understand Buyer Furnished Equipment,

The ELT is not BFE (buyer-furnished equipment). It is a buyer option for a piece of equipment that has been selected and certified by the OEM (in this case Boeing) and is factory installed by the OEM, and the only option that buyer has is "yes, I want it" or "no, I do not". The contract and payment is directly with the OEM, and not with the widget manufacturer (in this case ELT). Much like leather seats in a mass-produced car where cloth seats are the default.

BFE by its very definition means something a buyer has a choice of products / suppliers for, for example seats or galleys that have been certified by the OEM or where the buyer requests a certification be made as a condition of the purchase contract. The buyer enters into a contract directly with the seat or galley supplier for it and pays them directly, and the supplier ships to the airframe maker for installation. The shipping risk, delays, etc are borne by the buyer, not the OEM. The ELT is certainly not BFE.

Having said that, I think if it turns out the root cause of the fire was the ELT and the ELT alone and has nothing at all to do with the 787 ie (no contributing factors), and given this ELT is not made specifically for the 787 alone, then I do not see how the 787 can be held responsible for it. Much like if the altimeter fails on an A320 due to an internal fault, and the altimeter is not made specifically for the A320 alone, then the eventual fault will lie with the altimeter maker, not with Airbus.

[Edited 2013-07-20 15:42:10]

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: ComeAndGo
Posted 2013-07-20 15:57:55 and read 23469 times.

Quoting sankaps (Reply 139):
Having said that, I think if it turns out the root cause of the fire was the ELT and the ELT alone and has nothing at all to do with the 787 ie (no contributing factors), and given this ELT is not made specifically for the 787 alone, then I do not see how the 787 can be held responsible for it.

Except if the surrounding material the ELT is installed in turns out to be more flammable. The requirements for the installation of an ELT should have required adequate protection.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Daysleeper
Posted 2013-07-20 16:03:48 and read 23479 times.

Quoting garpd (Reply 112):
It is also strange how convoluted arguments get to blame Boeing. In your very own post for example

I'm sorry to burst you bubble but this being a Boeing aircraft they are solely responsible for the contained safe operation of the aircraft and all its subsystems; the buck stops with them - No two ways about it.

Besides, I've not yet seen issues such as excess condensation being ruled out as playing a part in the fault tree - If this does turn out to be the case, then the 787 is going to be knee deep in shit, and sinking fast.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: sankaps
Posted 2013-07-20 16:04:10 and read 23464 times.

Quoting ComeAndGo (Reply 140):
Except if the surrounding material the ELT is installed in turns out to be more flammable. The requirements for the installation of an ELT should have required adequate protection.

Sure, which is why I wrote " if it turns out the root cause of the fire was the ELT and the ELT alone and has nothing at all to do with the 787 ie (no contributing factors)". In your example, there is a contributing factor outside of the ELT alone.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: hivue
Posted 2013-07-20 16:21:59 and read 23467 times.

Haven't seen this posted yet -
http://www.forbes.com/sites/johngogl...oval-of-787-elts/?partner=yahootix

Excerpt:
"The FAA’s muted response appears to follow a disturbing pattern in the agency’s reaction to safety events related to the Boeing 787 aircraft. First, the FAA had to be nudged by the Japanese into grounding the fleet after problems with its lithium ion batteries caused extensive fire damage to a JAL aircraft parked in Boston and the emergency landing of an ANA 787. After the FAA lifted its grounding order, the Japanese ordered additional precautions before allowing its own carriers to resume 787 operations."

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: hivue
Posted 2013-07-20 16:32:38 and read 23338 times.

Quoting Speedbored (Reply 136):
The A330 pitot tubes met all certification requirents. The fact these turned out to be inadequate in service is hardly the manufacturers fault.
Correct. If anything the blame lies with EASA, or whichever group agreed the certification standards which seem to have proved to be inadequate for the weather that AF447 encountered.

The trouble is that the data the certificating authority relies on to make its judgment is mostly supplied by the airframe manufacturer, so the manufacturer will have to assume some of the responsibility if it turns out something their data said meets the certification criteria actually doesn't do that in service.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: garpd
Posted 2013-07-20 16:53:28 and read 23285 times.

Quoting multimark (Reply 121):

Is this ELT an off the shelf model? If so, why hasn't the same issue arisen on other a/c?

It's in use on 6000 aircraft or more. I think that qualifies it as off the shelf.

As for the issue never haven arisen before, that is not a valid argument.
A 777 had never crashed before until the BA038 incident. Did that make the incident any less believable?

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: spink
Posted 2013-07-20 17:04:14 and read 23251 times.

Quoting AirlineCritic (Reply 114):
Based on the amount of lithium in the ELT battery, I find it easy to believe it could start a fire. I find it less easy to understand how the fire spread. How fire resistant are, e.g., wiring and insulation expected to be in aircraft? The ELT battery can start a fire, but I do not believe it would be enough for the kind of damage seen on the hull. So what would be the fuel for the rest of the fire? Or would the energy in the ELT battery be enough light the CFRP itself in fire, in one specific location, and then letting the fire spread from there? Seems unlikely, but...

The batteries themselves contain enough energy to cause the fire damage seen. A laptop battery alone can cause a lot of damage, esp in an enclosed space. The cells in the ELT have almost a magnitude more energy than the common laptop battery.

And CFRP does not ignite. It like the actual circuit boards in the ELT is a flame retardant material. Both can be damaged by flame and heat but neither will actually self propagate a fire or thermal event. Once a given battery in the ELT went into thermal runaway, all the batteries would eventually hit thermal runaway and the fire they create can last quite a while just on their internal energy. It will be interesting to see if in the final report they have an estimated temperature for the ELT fire. They can estimate this from an examination of the ELT and which parts have melted or smoldered. Lithium-ion fires can reach core temperatures of over 600 Celsius.

Quoting mjoelnir (Reply 118):

A defect part chosen by Boeing for the B 787, even if it is optional, is the responsibility of Boeing.
Boeing can than fight it out with his supplier.

It was not a defective part, it was a part that had a defect. Neither Boeing nor Honeywell designed nor specified a defective part, instead Honeywell's manufacturing fault tests did not detect the defect within the part. If there was in fact a pinched wire within the ELT then it is likely that Honeywell will improve its manufacturing fault detection and testing.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: JoeCanuck
Posted 2013-07-20 17:21:40 and read 23208 times.

Quoting mjoelnir (Reply 127):

It is certainly fitted by Boeing, but it's not made by Boeing. If Boeing decided on putting an ELT on one of their planes, they go to an ELT manufacturer with their specifications and the pertinent certification standards. Basically, because ELTs are pretty standardised, Boeing basically picks an off the shelf model that suits its needs.

Boeing no more makes ELTs than it makes wheel nuts.

That doesn't mean it's not Boeing's responsibility to fix it. A buyer isn't responsible for chasing down the maker of each component, but that's a far cry from Boeing being responsible for causing the problem. It may not be their fault, (but maybe it is....we don't know yet), but it's still their responsibility as far as the customers are concerned.

Maybe Boeing will solve the problem by going to another ELT maker...there are a few to choose from.

Regardless, (presuming the ELT is the cause of the fire), Boeing will work out compensation with ET and Honeywell and we'll dilligently continue the search for the next thing which bring 787s raining from the heavens.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: kanban
Posted 2013-07-20 18:49:25 and read 22906 times.

Quoting mjoelnir (Reply 127):
The problem is just that the ELT is not a buyer furnished equipment.
Quoting sankaps (Reply 139):
The ELT is not BFE (buyer-furnished equipment).

Peace.. you guys may be right for current a/ps.. I can only go with practices in place during the time I was there.. the units maybe SFE.. on the other side, since neither have worked in the Boeing Procurement org, please don't tell me what their practices are.. The key thing neither BFE nor SFE get more than a shipping damage inspection and a nominal function test.

At any rate Reuters now says the crimped wire was caught between an access panel and the casing.. can happen to anybody in a hurry.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: WingedMigrator
Posted 2013-07-20 20:19:11 and read 22673 times.

Quoting spink (Reply 146):
And CFRP does not ignite.

  

Sounds like somebody needs a refresher course.

http://www.fire.tc.faa.gov/pdf/07-57.pdf

[Edited 2013-07-20 20:26:58]

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: NAV20
Posted 2013-07-20 20:28:05 and read 22691 times.

Now that the problem has been identified, one has to wonder what happens next? Looks as if Boeing are thinking in terms of replacing the whole rear fuselage section, flying the parts in and doing the repair at Heathrow:-

"Weber said there is a well-established procedure for applying a composite patch, either bonded or fastened to the existing skin. But he said it’s possible the damaged area is too big to be patched.

"In the worst case, he said, Boeing might have to replace the entire aft fuselage section, a single barrel-shaped piece measuring 19 feet in diameter and 23 feet long.

"In fact, this option could prove easier than patching. That’s because any fix will entail proving to the FAA that the repair is sound.

"Frank Abdi, chief scientist and founder of Long Beach, Calif.-based AlphaSTAR, which specializes in structural modeling and analysis of composite materials, said that to apply a substantial patch Boeing would have to do a computer simulation of the repair then “prove by analysis and by test that such a thing is possible.”

"Retired Boeing manager Ed Wilson, who worked with composites on the B-2 and 777 programs, said that replacing the entire back end could well be the quickest fix.

"Patching it, he said, “you’ll spend more time screwing around trying to convince regulators that it’s fixed.”

"Weber said replacing the entire rear-fuselage section is technically feasible.

"A Boeing Dreamlifter cargo plane could deliver a new section to Heathrow, where the plane would be jacked up in a hangar and the damaged section removed."


http://seattletimes.com/html/busines...17880_787fireinvestigationxml.html

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: LTC8K6
Posted 2013-07-20 22:12:46 and read 22298 times.

Quoting kanban (Reply 148):
Reuters now says the crimped wire was caught between an access panel and the casing.. can happen to anybody in a hurry.

Could someone have inspected the battery pack in the ELT and pinched the wire in the process?
You can change the pack in the ELT without removing the ELT, so there must be a panel to access the battery pack.

[Edited 2013-07-20 22:15:47]

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: sankaps
Posted 2013-07-21 00:28:42 and read 21886 times.

Quoting garpd (Reply 144):
A 777 had never crashed before until the BA038 incident. Did that make the incident any less believable?


Maybe I'm wrong, but wasn't the particular engine design / issue with the fuel-oil heat exchangers that caused the ice-formation to form, present only on the specific variant of the Rolls engine that was on 777s? So in that sense it is not an apples to apples comparison with the 787 ELTs, as it was not an "off the shelf" generic engine or RR and design issue that the 777 alone unluckily ran into?

Quoting kanban (Reply 147):
on the other side, since neither have worked in the Boeing Procurement org, please don't tell me what their practices are..

kanban -- with due respect, you do not know what our backgrounds are. At least one of us has significant experience with technical procurement (including BFE, SFE, and BSSFE) from both Boeing and Airbus, as a result of having done this for several years at a US major. Therefore speaking for myself, I am quite familiar with what the practices are and where responsibility and ultimate accountability for failures lies for various types of technical procurement parts and options. Regards.

[Edited 2013-07-21 00:49:55]

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: AirlineCritic
Posted 2013-07-21 00:32:00 and read 22203 times.

Quoting spink (Reply 146):
The batteries themselves contain enough energy to cause the fire damage seen. A laptop battery alone can cause a lot of damage, esp in an enclosed space. The cells in the ELT have almost a magnitude more energy than the common laptop battery.

I know laptop fires are dramatic. But to damage a strong CFRP hull for several square meters... hmm... and can you refresh my memory about the amount of energy and lithium in the batteries? They were quoted in some of the earlier threads but I cannot find the information right now. I seem to recall it was more than in a typical laptop battery, but not by 10x.

Quoting spink (Reply 146):
And CFRP does not ignite. It like the actual circuit boards in the ELT is a flame retardant material. Both can be damaged by flame and heat but neither will actually self propagate a fire or thermal event.

...

Quoting WingedMigrator (Reply 149):
http://www.fire.tc.faa.gov/pdf/07-57.pdf

Indeed, there seems to be some interesting reading here about the behaviour of carbon fibre materials. They do ignite, with the help of another fire (the possibly burning ELT) or even auto-ignite with enough heat. There are some specific numbers for required heat to ignite and heat generated during fire, maybe someone could calculate whether the ELT could get there.

There's also interesting reading about the behaviour of the material when it is heated or burns. The material expands, as the resin needs to escape as gas through the fibres.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: mjoelnir
Posted 2013-07-21 01:04:58 and read 21998 times.

Quoting garpd (Reply 144):
It's in use on 6000 aircraft or more. I think that qualifies it as off the shelf.

Even more reason to assume that something went wrong with the installation of that peace of equipment.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: PW100
Posted 2013-07-21 03:21:24 and read 21518 times.

Quoting garpd (Reply 112):
It is also strange how convoluted arguments get to blame Boeing. In your very own post for example. . . Assuming for the sake of argument, the ELT and it's battery are announced as the reason

You must be on to something; that must be the reason why Boeing is outsourcing so much, trying to become an integrator. If you don't build anything anymore, you can't be blamed if anything goes wrong.

To be clear. I'm being somewhat sarcastic off course. Just because the airframer didn't build it themselves doesn't mean that they don't have any responsibility. You go through great pains trying to explain why Boeing is not to blame; just because an ELT is an option, Boeing has no accountability over it??

Quoting kanban (Reply 119):
To understand Buyer Furnished Equipment

Thank you for this overview. If you think it thorough, it all makes a lot of sense off course.

Quoting kanban (Reply 119):
Now say you were buying a new car and asked the dealer to put a different tire on it (say a more aggressive tread) that the dealer does not stock but but can procure, if that tire has a manufacturing flaw that causes a blowout after a year, is the dealer responsible? Say your model came without GPS and you received one from your grandkids and installed it. Then you're driving along and it indicates a road intersection that doesn't exist and you drive off the road (believe me there are more than a few cases of people believing the GPS and not their eyes.), is the dealer responsible? after all they provided an electrical socket you plugged it into

This car is offered with the option of GPS (i.e. the brochure and pricing both includes and excludes the GPS system); I only have the option to choose the GPS system(s?) offered by the car manufacturer, I am not at freedom to choose and have the one from my grandkids installed.
I choose to have the GPS installed upon delivery and I PAY the car-OEM for both the unit’s purchase and installation.

A coupe of months after delivery of the car, because of a pinched wire somewhere in the GPS system (or its interface to the car) the GPS goes up in smoke, together with an important part of the car, you'll bet I'll be going back to my car dealer (who represents the car OEM). While the car-OEM may not be at fault because he did not build the GPS system, he still carries the full responsibility to me as a purchaser. I expect the car-OEM to go and solve the situation with the GPS manufacturer in terms of customer warranty and repair.
In their own interest, I would also expect the car-OEM and the GPS provider to come up with improved design and manufacturing/installation procedures.

The above is a complete different situation compared to your example. Do you have insight as to which example best describes the ELT installation in the 787?

Rgds,
PW100

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: garpd
Posted 2013-07-21 03:22:45 and read 21488 times.

Quoting mjoelnir (Reply 153):
Even more reason to assume that something went wrong with the installation of that peace of equipment.

Absolutely not. Assumption is the mother of all screw ups.
In an investigation, you do not assume anything.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: JoeCanuck
Posted 2013-07-21 06:09:15 and read 20924 times.

Quoting PW100 (Reply 154):

Few are saying Boeing isn't responsible for fixing the issue and taking care of the customers. What most, and I, am saying is that Boeing didn't cause the problem...as far as we know so far. IF the problem is internal to this specific ELT, then Boeing had nothing to do with it. It was caused by a manufacturer defect and Boeing isn't the manufacturer of the ELT, Honeywell is.

This is a device which almost no connection, (literally), to the systems on the aircraft. It's only connections are an auxilliary arming switch, an external antenna and its physical mounting hardware.

Though it is an electronic device, it is as self contained as a passenger's phone...even more isolated since it is not connected to any power systems on the aircraft and can't be charged in the aircraft.

Think of it as an old fashioned, D cell flashlight. The batteries are only discharged when in use and are never charged. It is regularly tested and after a certain period, the device is removed and the battery replaced.

If a flashlight went nova, like any other bit of Boeing installed equipment, Boeing would be responsible for the repair but they would not have caused the incident.

This is exactly how every aircraft manufacturer deals with ELT's. The 350 may have the identical mounting system...perhaps even the same model ELT.

I really don't think there is much in the way of coverup or conspiracy involved.

I know it's fun to blame all problems on Boeing, but it's looking unlikely they started this fire.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: AirbusA370
Posted 2013-07-21 06:35:35 and read 20767 times.

Quoting JoeCanuck (Reply 156):
I know it's fun to blame all problems on Boeing, but it's looking unlikely they started this fire.

Well, it is Boeing's responsibility to check if the environment where the ELT is installed is not harmful to the equipment. The "off the shelf" ELT is certified only to a certain level of heat/power spikes/emissions/humidity...

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: 2175301
Posted 2013-07-21 06:36:34 and read 20770 times.

Another possibility on responsibility.

It has been suggested above that perhaps the problem is from a pinched wire that was caught between and access panel and the housing - perhaps during routine maintenance such as checking or replacing the batteries. I certainly know that many pieces of equipment have to have the wires carefully stuffed back into the box when putting the cover on. It that is the case - then it may be the Airlines own maintenance group (or whoever the Airline contracted maintenance too) that is responsible for the fire as they would be the ones who pinched the wire.

Of course - the above is dependent on IF it is from a pinched wire between the access panel and the housing - and that service had been done to the ELT since installation.

I am sure that the AAIB is working to sort that all out (and it may not be from a pinched wire at all).

Have a great day,

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: JoeCanuck
Posted 2013-07-21 07:19:12 and read 20604 times.

Quoting AirbusA370 (Reply 157):

Actually, it is supposed to be a completely sealed, self contained unit and there are no power spikes, emissions, etc., because it is not connected to the aircraft electrical system.

The temperature ranges it must be able to withstand are mandated by whomever certifies the ELT, and installation. I find it very difficult to believe the crown environment of the 787 differs significantly from that of a 737, 330 or any other airliner.

Regardless, I'll reiterate; the ELT is sold, certified and installed as a sealed, self contained, waterproof, pre charged, not connected to any aircraft systems, unit....just like on every other aircraft with an ELT.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: JRenavitz
Posted 2013-07-21 07:26:54 and read 20557 times.

Quoting airtechy (Reply 129):
We will all move on until the next 1000+ post thread caused by a normal "introduction into service" problem.

I would think that most normal introduction into service problems don't cause mult-million dollar repairs, or the scrapping of a hull.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: flyingturtle
Posted 2013-07-21 07:53:48 and read 20411 times.

Hmm, is there a preliminary report out there? Or have I missed it?


David

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: by738
Posted 2013-07-21 08:12:07 and read 20300 times.

...and if this chat about patching and replacing barrel sections- what came of those who assured us it was a "write-off" ?

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: KC135R
Posted 2013-07-21 08:24:38 and read 20239 times.

One of the definitions of faith is "belief that is not based on proof" - there seem to be some people on here that have a great deal of faith, for whatever reason, that this incident is a 787 problem and, more to the point, indicative of a larger 787 design problem.

I admit, when I read the headline that a 787 was on fire in London last week my initial thought was "uh oh, here we go again". But as details began to emerge it became clear that this was a separate problem from the battery incident which caused the grounding. That did not mean, at that point, that it wasn't a 787 problem and there was a lot of speculation about what might have cause it based on what equipment is located in that area. Then the AAIB issued an interim report which seems place the focus squarely on the ELT. It is an interim report, and only time will tell, but there is very strong evidence to suggest that the ELT is the cause and, as such, I don't understand the response by some of "yeah, but..." I guess it's faith.

I see some similarity here to the SFO Asiana crash; some in the media began to speculate that it might have been an engine fuel flow problem as this was the cause of the only other 777 crash. At first glance, that could have been true; but as details emerged (not RR engines, approach speed extremely low, and engines responded to throttle inputs) it became clear that this was not the same thing as the BA crash - I don't understand why the same logic wouldn't apply here. I guess it's faith.

This article seems to add to the evidence that the ELT was the cause:
http://www.aviationweek.com/Article....e-xml/awx_07_21_2013_p0-599038.xml

"The new suspect in the search for a cause of the fire, which erupted in one of the 787’s emergency locator transmitters (ELT) while the aircraft was parked at London Heathrow Airport, emerged from forensic analysis..."

I don't see how someone's belief that the 787 is a flawed airplane should trump evidence gathered from forensic analysis. I guess it's faith.

"According to sources close to the investigation the remnants of the RESCU 406AFN showed evidence of a kink in the wiring which was likely related to its original assembly rather than something that could have occurred during its installation in the airframe."

I just don't see how the evidence at this point in time does anything other than basically absolve the 787 in this incident. Not that my opinion matters to anyone but me, but at this point in time I feel confident that this is not a 787 problem and could have happened on any of the 6,000 or so airplanes with this piece of equipment installed - if evidence comes out that contradicts that, I'll change my opinion.

Edited for clarity.

[Edited 2013-07-21 08:41:30]

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: KC135R
Posted 2013-07-21 09:06:48 and read 20068 times.

Quoting flyingturtle (Reply 161):
Hmm, is there a preliminary report out there? Or have I missed it?
http://www.aaib.gov.uk/publications/...s/s5_2013___boeing_787__et_aop.cfm

The report is a PDF file at the bottom of the page.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: kanban
Posted 2013-07-21 09:07:58 and read 20034 times.

Quoting PW100 (Reply 154):
This car is offered with the option of GPS (i.e. the brochure and pricing both includes and excludes the GPS system); I only have the option to choose the GPS system(s?) offered by the car manufacturer, I am not at freedom to choose and have the one from my grandkids installed.
I choose to have the GPS installed upon delivery and I PAY the car-OEM for both the unit’s purchase and installation.

maybe I used a bad example.. a neighbor just bought a car where the GPS was only an option if purchased in a package of stuff he didn't want , so he didn't buy the package.. but his grandkids then bought him one for his birthday... lucky guy. Now he did not crash it, that was another person entirely.. I was trying to stay away from the guy who bought a motor home and thought cruise control was auto pilot and went to make a cup of coffee. Then successfully sued the manufacturer for not make the difference clear.

Your scenario for options purchased through the dealer are correct..

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: airnorth
Posted 2013-07-21 11:03:21 and read 19417 times.

I guess I need a better understanding of the hypothesis that higher humidity in the 787 could contribute to this issue as a contributing factor. Because the cabin pressure and humidity is higher, there is a better chance of more condensation occurring during flight, freezing on the aircraft skin, then "raining", once the plane is back at lower altitudes or on the ground I suppose.
But I just cant see how a few percentage points in cabin humidity could play such a role, when other factors such as length of flight, and maybe even cruise altitude would also play a role. The way I understand it, warm moist cabin air has to find its way through the vapor barrier, and insulation, then finally contact the outer skin, before it can condense and freeze, then later thaw and "rain".
It just doesn't make sense to me that there would be a significant difference between the 787 and any other plane, to me, a more significant difference might be found in an older aircraft that has had the insulation and vapor barrier, disturbed or opened up for maintenance, allowing for more paths of cabin air to reach the outer skin, condense, freeze, then thaw and rain.
My personal experience with rain in the cabin is minimal, but i have seen significant amounts in both a 757, and a 330, both times after touching down in Honolulu.

Airnorth

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: TheRedBaron
Posted 2013-07-21 11:25:54 and read 19338 times.

Quoting JoeCanuck (Reply 159):
Regardless, I'll reiterate; the ELT is sold, certified and installed as a sealed, self contained, waterproof, pre charged, not connected to any aircraft systems, unit....just like on every other aircraft with an ELT.

Interesting!

Since the preeliminary report is VERY CAREFUL with its findings and we still have some pretty big questions regarding the event.... is it possible that the ELT failed due to external factors?

Just thinking outside the box...

TRB

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: ikramerica
Posted 2013-07-21 11:37:01 and read 19264 times.

Quoting hivue (Reply 142):
"The FAA’s muted response appears to follow a disturbing pattern in the agency’s reaction to safety events related to the Boeing 787 aircraft. First, the FAA had to be nudged by the Japanese into grounding the fleet after problems with its lithium ion batteries caused extensive fire damage to a JAL aircraft parked in Boston and the emergency landing of an ANA 787. After the FAA lifted its grounding order, the Japanese ordered additional precautions before allowing its own carriers to resume 787 operations."

I assume this article is an editorial and not news? Because the author has no idea what he's talking about.

"Nudged" into an unprecedented grounding of an aircraft never before seen in the history of aviation based on a non-fatal ground incident and an overreaction by a pilot in Japan? The author acts as if grounding of types is routine. It's not. Even after unexplained fatal crashes, it doesn't happen.

As for "extensive fire damage" again, that's bull. The aircraft did not have extensive fire damage.

Forbes must have a stake in Airbus.

Otherwise he would have pondered why the FAA was slow to ground the A380 after the engine explosion, the A330 after the unexplained Air France crash, the 777 after the BA crash, the 744 after the QF incident with the oxygen, etc.

If he were a real journalist, he'd be asking different questions about airline safety...

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: sankaps
Posted 2013-07-21 12:10:08 and read 19098 times.

Quoting ikramerica (Reply 168):
Forbes must have a stake in Airbus.

Otherwise he would have pondered why the FAA was slow to ground the A380 after the engine explosion, the A330 after the unexplained Air France crash, the 777 after the BA crash, the 744 after the QF incident with the oxygen, etc.

The same specious argument again.

Why would Forbes having a stake in Airbus prevent them from pondering on the 777 and 744 events you refer to above?

As discussed ad nauseum in various other threads, perhaps the common link is those were aircraft with either one-off events (the BA 777 and the QF A380) and / or were aircraft which flew for millions of hours before the said incidents occurred (the A330, 777 and the 744)?

As opposed to two alarming incidents of a similar nature occurring within days of each other on a new aircraft type when the probability of even one such incident occurring was calculated to be microscopically small, and another lithium battery and fire-related event happening within weeks of the aircraft being back in operation (albeit in a different component from the previous two.)

[Edited 2013-07-21 12:31:07]

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: flyingturtle
Posted 2013-07-21 13:37:06 and read 18585 times.

Quoting KC135R (Reply 164):

Thank you!


Perhaps irrelevant: Has the CFRP fuselage a different thermal conductivity than aluminum? If parked in the sun, does the interior heat faster than in conventional airplanes?


David

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: JoeCanuck
Posted 2013-07-21 15:03:48 and read 18195 times.

Quoting TheRedBaron (Reply 167):

Since no final report has been released, we don't even know it really is the ELT....but that seems to be the latest, most likely culprit. The ELT is neither powered by the 787 nor does it have to be grounded to it but it may have been grounded in the way it was mounted.

Again, it is very much like a flashlight....completely self contained and fully functionable whether or not it is actually mounted on the aircraft.

External factors could very well have played a part...we just don't' know yet...for instance, if the battery was punctured, (which has not been suggested by investigators as a factor).

The fuselage being composite seems to me to be a red herring, for this one. If you took an aluminum box and an identical CFRP box and placed them in the Ethiopian elements, I suggest the temperatures within would remain close to each other.

Boeing mollested plenty of pooches with the 787 and deserve much of the derision they received. This time, however, I suspect they are much more victims than perpetrators.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Klaus
Posted 2013-07-21 15:48:42 and read 18004 times.

Quoting JoeCanuck (Reply 171):
The ELT is neither powered by the 787 nor does it have to be grounded to it

Really? That would sound like a safety hazard, with static charges building up from the ELT antenna, and with no grounding pulling not just the ELT itself but also the entire control wire bundle to the cockpit right down to the cockpit control switch to that floating potential until hitting an unsuspecting pilot coming close to that switch or sparking to a neighbouring wire bundle.

That would sound pretty dangerous to me.

Just by thinking this through I'm rather certain that there needs to be pretty solid grounding of the ELT, even if that common ground connection is the only thing it shares with the rest of the plane electrically.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: PITingres
Posted 2013-07-21 17:10:38 and read 17727 times.

Quoting flyingturtle (Reply 170):
Perhaps irrelevant: Has the CFRP fuselage a different thermal conductivity than aluminum? If parked in the sun, does the interior heat faster than in conventional airplanes?

This came up in part 5 too. Yes, CFRP has a different thermal conductivity, but no, I very much doubt that that would have anything to do with interior heating rates. Paint color, interior insulation, window size and shading will all have a much greater effect. Interior heating is a slow process and I can't imagine that conduction thru the small dimension of the skin is a rate limiting step.

Where CFRP might, maybe, possibly matter in an event of this sort is local heating. With aluminum, ignoring insulation (which you probably can't but let's ignore it anyway), the entire airplane acts as a sort of heat sink and it's a lot harder to get a local hot-spot. Aluminum is a comparatively lousy heat conductor but it's a lot better than CFRP I should think. With CFRP it ought to be easier to get a local hot-spot given a heat source, such as a malfunctioning ELT. On the other hand, the ELT presumably isn't mounted directly to the frame even in an aluminum airplane so there's a heat barrier there one way or another. This is where it would be nice to have some facts...  

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: WingedMigrator
Posted 2013-07-21 17:53:03 and read 17578 times.

Quoting PITingres (Reply 173):
Aluminum is a comparatively lousy heat conductor

Compared to what? Copper? Gold? Compared to most materials, aluminum is an excellent heat conductor.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: B777fan
Posted 2013-07-21 18:28:53 and read 17434 times.

Quoting Klaus (Reply 172):
I'm rather certain that there needs to be pretty solid grounding of the ELT

ELT's are grounded at the antenna ground plane.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: cornutt
Posted 2013-07-21 18:33:51 and read 17472 times.

Quoting airnorth (Reply 166):
I guess I need a better understanding of the hypothesis that higher humidity in the 787 could contribute to this issue as a contributing factor.

I'm not sure I get that either. The ELT is supposed to be able to survive both a crash and being under water to a considerable depth. Doesn't seem like a little humidity should have any effect on it. Unless maybe the battery compartment cover (assuming it has such a thing) wasn't secured properly -- pinched wire prevented it from sealing? -- and it allowed humidity into the case.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: cornutt
Posted 2013-07-21 18:44:42 and read 17716 times.

Quoting PW100 (Reply 154):
To be clear. I'm being somewhat sarcastic off course. Just because the airframer didn't build it themselves doesn't mean that they don't have any responsibility.

I get what you're saying and I agree in general. We've all had an experience like this: you contract with Home Depot or Lowe's or someplace to do some work on your house; they do a crappy job, and when you go back to the store to complain, they tell you, "Oh, a contractor did that work. We're not responsible." Not only is it infuriating because of the number of hoops you have to jump through to get it fixed, but it's dishonest marketing.

Having said that, the ELT is something of a special case because it's a self-contained system that doesn't interact very much with the rest of the aircraft. It would be like this: you build a house. The electric utility tells you that you have to install a specific meter socket. You do, and then a few months later it shorts out and burns down your house. Insurance refuses to pay because they said you installed a defective meter socket. Well yeah, you did install that meter socket, but you had no choice in the matter -- you had to do it the way the power company told you. A more immediate applicable example might be: what if, say, the CVR started a fire onboard?

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: nomadd22
Posted 2013-07-21 18:49:33 and read 17696 times.

Quoting B777fan (Reply 175):

ELT's are grounded at the antenna ground plane.

What ground plane? Do they connect to the bronze mesh?

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: CO953
Posted 2013-07-21 19:52:58 and read 17531 times.

Quoting cornutt (Reply 176):
I'm not sure I get that either. The ELT is supposed to be able to survive both a crash and being under water to a considerable depth. Doesn't seem like a little humidity should have any effect on it. Unless maybe the battery compartment cover (assuming it has such a thing) wasn't secured properly -- pinched wire prevented it from sealing? -- and it allowed humidity into the case.

Someone busted my noob chops a few days ago when I mentioned that the ELT would be important in case of a disappearance over water, by saying that the ELT doesn't work underwater and so wouldn't have to be waterproof.

Just bringing that up. Not gainsaying you.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: flood
Posted 2013-07-21 20:08:05 and read 17506 times.

Quoting cornutt (Reply 176):
The ELT is supposed to be able to survive both a crash and being under water to a considerable depth.

According to Reuters:

"The ELT must pass a test to prove it can be submerged under one meter of water for one hour."
http://www.reuters.com/article/2013/...nvestigation-idUSBRE96I18020130720

I don't think they're as rugged as one would think.

Quoting JoeCanuck (Reply 171):
Since no final report has been released, we don't even know it really is the ELT

Thank you. For a while there, from reading a couple of the above comments I thought I missed the AAIB report identifying the ELT as the root cause.

That said, a crushed wire in the battery cover might not necessarily damage the wire's insulation, but could easily compromise the seal. Would be nice to have a picture to see how they're installed on a 787.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: jetsetter1969
Posted 2013-07-21 20:28:54 and read 17447 times.

Not working in the airline industry I might be off the mark but what is it that makes the 787 "seem" so problematic?

Inflight fire on the 787 as such is not unique (swissair md11, Air Canada dc-9, SAA 747combi) the question I have is that where a fire occurs at altitude does the aluminium aircraft have any perceptible additional time as the aluminium hull would act like a heat sink and disperse the heat compared to CFRP thus allowing precious minutes to get the aircraft on the ground?

Is the a350 CFRP panels so if a similar event to the Heathrow one occurred that individual panels could be replaced making repairs easier?

Does the use of electrically driven systems rather than bleed air on the 787 pose any higher risk to failure due to higher electrical loads, residual voltages when shut down etc?

In the case of the Heathrow incident does the ELT have any history of any similar failure in other aircraft? If so what battery type and wiring/housing similarities

There was comment in an earlier thread of the 787 batt box having a vent tube or similar to vent smoke and/or heat from a cooking battery would something similar work for venting condensation near the ELT area?

cheers

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: B777fan
Posted 2013-07-21 21:00:24 and read 17332 times.

Quoting nomadd22 (Reply 178):
Quoting B777fan (Reply 175):

ELT's are grounded at the antenna ground plane.


What ground plane? Do they connect to the bronze mesh?

I don't know the mechanics of connecting to the ground plane on the 787 but one is needed for the antenna. It's easy on a metal airplane but on CFRP aircraft the ground plane must either be integrated into the aircraft skin or into the antenna itself.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: kanban
Posted 2013-07-21 21:11:09 and read 17284 times.

Quoting B777fan (Reply 183):
I don't know the mechanics of connecting to the ground plane on the 787 but one is needed for the antenna. It's easy on a metal airplane but on CFRP aircraft the ground plane must either be integrated into the aircraft skin or into the antenna itself.

or they could run a grounding wire to the nearest metallic piece of structure, say at a section join.. because the bonding and grounding has to span the section joints.. I think any hull penetration if done properly could provide contact with the grounding layer.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: PITingres
Posted 2013-07-22 02:48:31 and read 16327 times.

re aluminum heat conduction:

Quoting WingedMigrator (Reply 174):
Compared to what? Copper? Gold? Compared to most materials, aluminum is an excellent heat conductor.

I was thinking compared to many metals, but I just took a look at a table and it's not bad. Aluminum is (much) worse than copper, silver, gold, and a few others, but better than many other metals including steel.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: nomadd22
Posted 2013-07-22 03:59:53 and read 15977 times.

Quoting kanban (Reply 183):
Quoting B777fan (Reply 183):
I don't know the mechanics of connecting to the ground plane on the 787 but one is needed for the antenna. It's easy on a metal airplane but on CFRP aircraft the ground plane must either be integrated into the aircraft skin or into the antenna itself.

or they could run a grounding wire to the nearest metallic piece of structure, say at a section join.. because the bonding and grounding has to span the section joints.. I think any hull penetration if done properly could provide contact with the grounding layer.

I'm not sure if any ground plane or grounding at all needs to be assumed. The thing is just an EPIRB by another name, isn't it? If it has a through hull antenna, it might be better if it was isolated for lightning reasons. The device would be unprotected, but less likely to get hit by lightning in the first place and you wouldn't have to meet whatever grounding standards anything electrically connected to the aircraft has to meet.

[Edited 2013-07-22 04:02:09]

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Pugman211
Posted 2013-07-22 04:12:25 and read 15869 times.

Is the aircraft outside now or still in a hangar? Any fresh pictures if it is outside?

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: KC135R
Posted 2013-07-22 05:46:37 and read 15552 times.

Interesting article about repairing the damage:

http://www.aviationweek.com/Article....l/AW_07_22_2013_p22-598174.xml&p=1

Also of note, this quote:

The aircraft maker also points out that although the fire was severe enough to visibly char the exterior of the skin, the fire did not penetrate the surface.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Klaus
Posted 2013-07-22 06:24:59 and read 15178 times.

Quoting KC135R (Reply 187):
Also of note, this quote:

The aircraft maker also points out that although the fire was severe enough to visibly char the exterior of the skin, the fire did not penetrate the surface.

One of the questions being whether that would still have been true in flight, with aerodynamic forces and pressurization added to the situation.

And the structure still needs to be replaced.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: hivue
Posted 2013-07-22 07:40:30 and read 14860 times.

From the Reuters article linked in flood's reply 180 above:

"Boeing installs the beacons in different areas of the plane, depending on an airline's preference and its home country's regulations."

ET does not opt for the crew rest area, apparently normally located where the ELT is.

"The AAIB also is looking at the placement of the ELT, which is bolted onto a bracket attached to the frame of the plane - exactly where condensation builds up, one of the sources said."

"'Condensation, humidity and installation - that's the focal point of the investigation,' the source said."

Perhaps the holes are starting to line up?

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: rcair1
Posted 2013-07-22 08:25:50 and read 14552 times.

Quoting golfradio (Reply 3):
How is the battery charged if it is not connected to the aircraft's bus?

It is not. The battery is not rechargeable.

Quoting WestWing (Reply 4):
I guess for a device with batteries that cannot be removed, the only way to achieve "inertness" is to remove the ELT in toto?

The battery can be replaced, hence removed, without removing the ELT

Quoting Klaus (Reply 18):
That's not the point – if the ELT (or a related component) should have been cooked with power from the main supply due to a short, such fault currents would most likely turn up in the log of a power monitor

Cooked by mains connected to what wire. The 22 gauge wire to the control runs? If line voltage was applied to those they would fuse (vaporize) very very quickly and the event would be over. There would also be evidence along the wire run so I suspect we would have heard. BTW - what mains? The power to the a/c was off.

Quoting Stitch (Reply 20):
But based on the post of an employee of a 787 operator, it appears the ELT is not near any power conduits. So could such an event happen? Does anyone know the voltage and current of the wires that are connect the ELT to the cockpit?

The spec sheet says 22 gauge. Very small. They are signal lines.

Quoting gators312 (Reply 23):
Could a lightning strike in flight to the ELT antenna have begun the thermal runaway of the battery inside the ELT?

They probably would have seen the damage to the antenna from the lightening strike. No report of that.

Quoting Speedbored (Reply 33):
I also fail to see how shorting out two data cables could cause a problem. It probably happens many times a day in offices all over the world without problems.

Correct. The people latching on this are hypothesizing some line voltage got onto the signal lines some hours before the fire was detected and somehow caused the batteries in the ELT to fail causing the fire.

Quoting seahawk (Reply 35):
This would the third battery containment failure in the 787. My gut says, this is unlikely to be bad luck.

Huh? What is the connection.
This is like saying that both a tail light and head light on my car burned out - so they must be connected. No - not even that much - the tail light and head light are connected. More like the tail light and the bulb in the flashlight in the glove box.

Quoting FlyingAY (Reply 44):
I'm sure there are more iPhones (not mentioning other consumer electronic devices) on every flight than there are ELTs, yet no iPhone in the cabin has caused such an extensive damage to a plane.

Leave an iphone unattended (or laptop) and it most certainly could cause this damage if a failure happened - maybe not an iphone - not much energy there. A laptop- yes.
Wasn't there just a fire aboard an aircraft they suspect was caused by a consumer battery in luggage?

Quoting sphealey (Reply 48):
While I'm linking things   Here's a calculator for estimating the fusing (melt-through) current for copper wire at various gauges. For 24 gauge solid wire (instrument wire) I get a 5-second melt-through current of ~29 amps.

Reasonable - maybe faster. Will depend on the voltage. A higher voltage will fuse faster.

Quoting Speedbored (Reply 49):
In any electrical system with things regularly switching on and off, voltage spikes will be created by the switching, even when using solid-state switches.

Are you presuming some voltage spike through - what - the ground?

Quoting Daysleeper (Reply 50):
The 787 uses a distributed power system, with multiple RPDU's (sorta like substations) throughout the aircraft. As far as I'm aware this system was introduced with the 787 and is unique.

And there is no indication in the AAIB report that RPDU's were related at all.

Quoting hivue (Reply 55):
accepted scientific theory began life as a belief.

No - at best they begin as a hypothesis.

Quoting seahawk (Reply 65):
The only idea I could offer is the variable frequency starter generator.

And how is that related to a device not connected to it and when the VFSG is off?

Quoting spacecadet (Reply 73):
"Theorize, then test"

Hypothesize.

Quoting mjoelnir (Reply 153):
Even more reason to assume that something went wrong with the installation of that peace of equipment.

Why? You have a reliable piece of equipment that is very standardized, easy to install and with low system integration - why would you assume the simple outside is more likely to fail that the complex inside. There is no basis for this assumption. (Assume = make and Ass of U and Me.)

Quoting garpd (Reply 155):
Absolutely not. Assumption is the mother of all screw ups.
In an investigation, you do not assume anything.

  

Quoting jetsetter1969 (Reply 181):
perceptible additional time as the aluminium hull would act like a heat sink and disperse the heat compared to CFRP thus allowing precious minutes to get the aircraft on the ground?

Compared to the heat in this fire, the sinking capabilities of the aluminum would be insignificant unless the aluminum was conducting it to a large heat sink. - even then - probably not.

Quoting nomadd22 (Reply 185):
I'm not sure if any ground plane or grounding at all needs to be assumed. The thing is just an EPIRB by another name, isn't it? If it has a through hull antenna, it might be better if it was isolated for lightning reasons. The device would be unprotected, but less likely to get hit by lightning in the first place and you wouldn't have to meet whatever grounding standards anything electrically connected to the aircraft has to meet.

No - floating an antenna above ground on a an aircraft that, itself, is not grounded - will have no impact on where lightning may or may not hit. Lightening does not care about electrical fields as small as would be created between a floating antenna and the body.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: seahawk
Posted 2013-07-22 08:51:38 and read 14326 times.

Quoting rcair1 (Reply 190):
Huh? What is the connection.
This is like saying that both a tail light and head light on my car burned out - so they must be connected. No - not even that much - the tail light and head light are connected. More like the tail light and the bulb in the flashlight in the glove box.

Batteries are also affected by environment conditions. Humidity, temperature of vibration for example. And as I explained in my previous posts, the fact that all those batteries were installed in aluminium casing at the time of the incidents, lets me consider the possibility that it could be condensation playing a part. Especially as Honeywell said that the type of ELT is installed in many other planes, without having such a major thermal event before.

Quoting rcair1 (Reply 190):
And how is that related to a device not connected to it and when the VFSG is off?

It was an answer to the question, if any part on the 787 could possibly create vibrations of a frequency unique to the 787.

[Edited 2013-07-22 08:52:11]

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: zeke
Posted 2013-07-22 08:54:00 and read 14470 times.

Been another 787 removed from service today that was being prepared for departure. Apparently due to smoke like substance coming from the after cargo hold in Doha. No further details, just preliminary.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: nomadd22
Posted 2013-07-22 09:09:35 and read 14264 times.

Quoting rcair1 (Reply 190):
No - floating an antenna above ground on a an aircraft that, itself, is not grounded - will have no impact on where lightning may or may not hit. Lightening does not care about electrical fields as small as would be created between a floating antenna and the body.

I've been repairing lightning damaged communications and figuring out way to prevent it for over 30 years. If lightning hits the top of the plane near that antenna for any reason, it's going to find the antenna. Even if the ELT doesn't have a solid ground to the plane, it's not going to be isolated enough that it's not at ground potential and lightning current is going in. That means the potential between the antenna center conductor and the reference, or shield, is liable to be pretty extreme for a few milliseconds and cause untold damage inside the unit.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Speedbored
Posted 2013-07-22 09:17:16 and read 14177 times.

Quoting rcair1 (Reply 190):
Are you presuming some voltage spike through - what - the ground?

Given that voltages are measured in relation to the ground, it would be impossible to have any spikes through the ground. No. I'm talkiing about whatever lines are being switched, whether it's power or data lines.

Quoting rcair1 (Reply 190):
And how is that related to a device not connected to it and when the VFSG is off?

Given that the discussion was about vibrations, pretty much everything on the aircraft is connected. And, unlike many people, I was not assuming that whatever started this fire triggered it when the power was off. The AAIB has not, at present, released any information about when the fire started, just when it was noticed, which will be an inderterminate amount of time after it started.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Speedbored
Posted 2013-07-22 09:21:54 and read 14158 times.

Quoting nomadd22 (Reply 185):
I'm not sure if any ground plane or grounding at all needs to be assumed.

Given that the ELT has cables leading from it to a switch in the flightdeck, and may also (depending on which previous posters you believe) have a data connection to a data concentrator to supply data for ACARS, it would be a very bad design indeed if it was not grounded to the aircraft.

Even without a connection to anything other than a switch in the flightdeck, if the ELT was not grounded, it could potentially build up sufficient static charge for arcing to occur from the switch or connecting cables.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Klaus
Posted 2013-07-22 09:33:07 and read 14091 times.

Quoting rcair1 (Reply 190):
Cooked by mains connected to what wire. The 22 gauge wire to the control runs? If line voltage was applied to those they would fuse (vaporize) very very quickly and the event would be over. There would also be evidence along the wire run so I suspect we would have heard.

I've been saying that a while ago: Checking the wires connected to the damaged area would be a standard part of the investigation, easily ruling out the control lines as a source if nothing was found there.

Quoting rcair1 (Reply 190):
BTW - what mains? The power to the a/c was off.

28V is easily enough to cause an electrical fire if the current is strong enough, but there the wire strength is a valid argument.

Quoting rcair1 (Reply 190):
Compared to the heat in this fire, the sinking capabilities of the aluminum would be insignificant unless the aluminum was conducting it to a large heat sink. - even then - probably not.

No, this can make a big difference, because even just spreading the heat over a few square meters can suck so much energy from a concentrated heat source such as a runaway battery that the remaining temperature is no longer sufficient to actually start a fire.

An aluminium fuselage is a huge heat sink by itself, by the way, with lots of external area exposed to air convection.

Thermal insulation can be dangerous in such a scenaro, because it leaves the heat concentrated in a small area which leads to much higher temperatures there, potentially to the point of ignition of nearby substances.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: sankaps
Posted 2013-07-22 09:38:13 and read 14071 times.

Quoting zeke (Reply 192):
Been another 787 removed from service today that was being prepared for departure. Apparently due to smoke like substance coming from the after cargo hold in Doha. No further details, just preliminary.

Let's hope it was just something in the cargo or pax luggage.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: 1337Delta764
Posted 2013-07-22 10:13:37 and read 13906 times.

Quoting zeke (Reply 192):
Been another 787 removed from service today that was being prepared for departure. Apparently due to smoke like substance coming from the after cargo hold in Doha. No further details, just preliminary.

Oddly, the media has been rather silent about this incident. I looked on Google, and all I found was a thread on another forum, which was posted about 10 hours ago.

[Edited 2013-07-22 10:14:48]

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Pygmalion
Posted 2013-07-22 10:20:51 and read 13816 times.

Quoting seahawk (Reply 191):
Batteries are also affected by environment conditions. Humidity, temperature of vibration for example. And as I explained in my previous posts, the fact that all those batteries were installed in aluminium casing at the time of the incidents, lets me consider the possibility that it could be condensation playing a part. Especially as Honeywell said that the type of ELT is installed in many other planes, without having such a major thermal event before.

Humidity and condensation from what?? This red herring keeps coming up... with no basis in reality. You get condensation in flight from the cold skin of the airplane being below the dew point of moisture laden air inside the fuselage. Moisture from passengers 200+ breathing into the air. This airplane was parked, on the ground, in the sun, no passengers. Where is the cold heal sink that is below the local dew point that would cause all this condensation from moisture laden air??? Moisture from what source?? The crown of the that airplane was sitting in the sun and was hot not cold, The ELT is on the passenger side of the insulation and not the skin side and is close to the same temperature as the passengers. The ELT was at the same temperature as everything around it. You only get condensation from temperature differentials between the air and a cooler part exposed in that cooler moisture laden air. Are you saying that the ELT had its own refrigeration system and that it caused it to be cold and moisture to condense on it???

This is a bad supposition with no basis in elementary physics. And now the journalism majors on the news are saying this as fact as well.

The 787 has more humidity in the cabin in flight because its designed that way for passenger comfort. On the ground with the doors open, its the same as any other airplane.

If you are saying that the previous flights humidity levels perhaps had something to do with it... fine, that could ba a reasonable supposition... but since the ELT is also designed to survive being immersed in water... it still should have had no effect from design perspective.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: B777fan
Posted 2013-07-22 10:37:26 and read 13681 times.

Quoting kanban (Reply 183):
or they could run a grounding wire to the nearest metallic piece of structure

Well, there has to be a ground plane around the antenna for it to work. It can't be displaced away from the antenna. I would find it very odd that they would run a feed line to the antenna and a separate ground to something else away from the antenna that connects up to the imbedded metallic mesh in the skin. I'm also not sure how well that would work.

My antenna for the ELT I installed in the plane I built has a simple 1/4 wave antenna. It must sit on something metallic for it to radiate correctly. In my case that is the aluminum skin itself. If I had built a carbon fiber aircraft I would have had to embed some kind of metal foil into the skin to serve as the ground plane for the antenna.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: GCT64
Posted 2013-07-22 10:52:41 and read 13652 times.

Quoting Pugman211 (Reply 186):
Is the aircraft outside now or still in a hangar? Any fresh pictures if it is outside?

It's on stand 616 [Cargo cul-de-sac where the DLH A300s park] - not seen any fresh pictures.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: B777fan
Posted 2013-07-22 10:54:35 and read 13957 times.

Quoting nomadd22 (Reply 185):
The thing is just an EPIRB by another name

Yes, and internal to that EPIRB there is a feed line to the antenna with a ground to some kind of antenna ground plane. As folded up as it might be, it is there.

The ELT does not have to be grounded to the aircraft ground. It could connect to a stand alone antenna that has the ground plane built in. In that case the ELT ground would be floating in relation to the airplane ground. I would guess that is not likely.

As pointed out by another poster, if the ELT connects up to any other equipment, even to just signal that it is on, then it would be bad practice to not have it grounded to the aircraft.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Stitch
Posted 2013-07-22 11:01:57 and read 14039 times.

Quoting Klaus (Reply 188):
One of the questions being whether that would still have been true in flight, with aerodynamic forces and pressurization added to the situation.

The AviationWeek article noted the structure held up "very well" and Boeing's tests showed that the 787's fuselage exhibited longer burn through times than aluminum fuselage sections.

So if this had happened in flight, the 787 may very well have faired better than, say, a 767.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: bikerthai
Posted 2013-07-22 11:11:30 and read 13868 times.

Quoting Pygmalion (Reply 199):
Humidity and condensation from what?? This red herring keeps coming up... with no basis in reality.

Not a red herring. If the ELT has an air path to the outside air (venting or gaps caused by improper access cover installation) then after several flight cycle, there could be water condensing inside it. If not properly drained, corrosion of terminals or exposed wiring could occur even if the moisture eventually evaporate while sitting on the ground.

bt

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: nomadd22
Posted 2013-07-22 11:42:18 and read 13698 times.

Quoting Speedbored (Reply 195):
Given that the ELT has cables leading from it to a switch in the flightdeck, and may also (depending on which previous posters you believe) have a data connection to a data concentrator to supply data for ACARS, it would be a very bad design indeed if it was not grounded to the aircraft.

Even without a connection to anything other than a switch in the flightdeck, if the ELT was not grounded, it could potentially build up sufficient static charge for arcing to occur from the switch or connecting cables.

Devices that need to stay electrically isolated are just connected to readouts or control lines through simple opto-isolator switches. It would be very understandable to do an ELT that way to keep lightning strikes or other system electrical disasters from affecting the ELT. And million ohm or so resistors are used to ground things when you want to stay relatively isolated, but still keep from building a charge.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Stitch
Posted 2013-07-22 13:00:05 and read 13328 times.

Quoting bikerthai (Reply 204):
Not a red herring. If the ELT has an air path to the outside air (venting or gaps caused by improper access cover installation) then after several flight cycle, there could be water condensing inside it. If not properly drained, corrosion of terminals or exposed wiring could occur even if the moisture eventually evaporate while sitting on the ground.

If the device is designed to survive under a meter of water for an hour, I would expect it's normally a sealed unit. That being said, if the battery access was not properly sealed, then it does not seem outside the realm of possibility that condensation was able to form inside the battery compartment if the relative humidity was high enough.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: airtechy
Posted 2013-07-22 13:01:45 and read 13369 times.

Quoting bikerthai (Reply 204):

Not a red herring. If the ELT has an air path to the outside air (venting or gaps caused by improper access cover installation) then after several flight cycle, there could be water condensing inside it. If not properly drained, corrosion of terminals or exposed wiring could occur even if the moisture eventually evaporate while sitting on the ground.

I'm sorry this was practically a brand new ELT. The device type is certified to a water depth of one meter for a short time. The chance of internal moisture or corrosion being a factor is -1 or a scale of 1 to 10. It probably encountered more humidity pre-install setting on a shelf in Seattle rather than on this airplane also. I doubt if even the fireman's hose water would have caused a problem with an intact ELT.  

AT

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: bikerthai
Posted 2013-07-22 13:10:55 and read 13252 times.

Quoting airtechy (Reply 207):
It probably encountered more humidity pre-install setting on a shelf in Seattle rather than on this airplane also. I doubt if even the fireman's hose water would have caused a problem with an intact ELT.

True, not out of realm of possibility that any access panel was removed and reinstalled at Seattle for a variety of reasons.

One of which could be (pure speculation here) that the battery failed during installation check and they went in and replaced it.

As we have seen in these types of "accidents" several things have to happen in order a failure of this magnitude would occur.

So water in the unit in itself may not cause a problem. A crimped wire by itself may not be a problem. But combine the two you may have something to worry about.

bt

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: ikramerica
Posted 2013-07-22 13:58:08 and read 13079 times.

Quoting airtechy (Reply 207):
I'm sorry this was practically a brand new ELT. The device type is certified to a water depth of one meter for a short time. The chance of internal moisture or corrosion being a factor is -1 or a scale of 1 to 10. It probably encountered more humidity pre-install setting on a shelf in Seattle rather than on this airplane also. I doubt if even the fireman's hose water would have caused a problem with an intact ELT.  

Yes, considering it is new, my guess is that it had never self-tested itself after being installed in the aircraft, and according to some posters, it self-tests once a month, and it may have melted down during it's FIRST in situ self test due to crimped wiring that shorted out inside the unit.

But if that's the case, why didn't it fail during the manual tests that must have been performed during installation?

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: airtechy
Posted 2013-07-22 14:11:39 and read 12983 times.

Quoting ikramerica (Reply 209):

But if that's the case, why didn't it fail during the manual tests that must have been performed during installation?

An interesting point and I have no clue. I don't know what wiring they use internal to the ELT, but at one time there was a problem with Kapton wiring which was used because the insulation is lighter and thinner then normal insulation. As I recall, it has teflon insulation which has a tendency to cold flow. A pinch against metal might take a while to cause a short. Who knows when this ELT was manufactured, but with the "just in time" manufacturing plan probably not long before installation.

Thermal cycles can also cause problems to show up. Don't ask me how I know.  

AT

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: ikramerica
Posted 2013-07-22 14:20:28 and read 12968 times.

Quoting airtechy (Reply 210):
An interesting point and I have no clue. I don't know what wiring they use internal to the ELT, but at one time there was a problem with Kapton wiring which was used because the insulation is lighter and thinner then normal insulation. As I recall, it has teflon insulation which has a tendency to cold flow. A pinch against metal might take a while to cause a short. Who knows when this ELT was manufactured, but with the "just in time" manufacturing plan probably not long before installation.

Thermal cycles can also cause problems to show up. Don't ask me how I know.  

Interesting thought there.

So it might be that yes, it WAS a hot day, for London. Yes, the crown space DID heat up. The wiring was already crimped and possibly melted from initial install and testing, and after use, the insulation had finally reached a point of complete penetration. The hot day caused the insulation to expand just enough to allow metal on metal, the self-test initiated during the time the aircraft is baking in the sun with all systems off, and voila! Shorting of DC power wires and a battery fire.

Stranger things have happened...

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: bikerthai
Posted 2013-07-22 14:25:58 and read 12995 times.

Quoting airtechy (Reply 210):
Who knows when this ELT was manufactured, but with the "just in time" manufacturing plan probably not long before installation.

LOL, actually considering that the 787 program was delayed by how many months? years? I wouldn't place my bet that this ELT was a "just in time" unit. Small items like the ELT are bought in batch and I would not be surprised if the ELT installed would have been in Boeing's hands when they first rolled out the ANA airplane.

bt

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: airtechy
Posted 2013-07-22 14:28:33 and read 12956 times.

I would be more inclined to think that the short occurred on a wire which in and of itself caused a heavy current flow without requiring a self test to coincide.....such as the battery cable itself.

AT

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: KELPkid
Posted 2013-07-22 15:04:20 and read 12911 times.

Quoting ikramerica (Reply 209):
Yes, considering it is new, my guess is that it had never self-tested itself after being installed in the aircraft, and according to some posters, it self-tests once a month, and it may have melted down during it's FIRST in situ self test due to crimped wiring that shorted out inside the unit.

According to all things 787, ET-AOP was delivered in 2012. The ELT shoud have done its monthy self test a few times by now...the FAR's require it. The unit is to be tested (or self-tested as the case may be   ) once a month in a 5 minute window on the hour (this is the agreed upon ELT self-test time, so that if you test an ELT during this time, the signal is not confused for a bona-fide ELT activation). Any ELT activation outside this window is considered by SAR parties to be genuine.

You are right, though, perhaps the conditions were "just right" this time for a fire to erupt during the self-test...but then again, for all we know, maybe the electrons were just given the large escape path to ground that they needed by temperature, humidity, and solar heating alone?

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: PITingres
Posted 2013-07-22 15:19:46 and read 12750 times.

Quoting nomadd22 (Reply 205):
Devices that need to stay electrically isolated are just connected to readouts or control lines through simple opto-isolator switches.

s/ are / should be / (and yes I'm showing my age and editor preference)

One would like to assume these things, yes. Are the control lines really opto-isolated, does anyone know? Not that I see it as a big deal for this particular incident. As others have pointed out, if the ignition source was a surge from a short on the control lines, they ought to show signs of that since they're only 22 gauge. (I remember zorching wires with a 6v lantern battery as a kid, and those were 22 or maybe 24 gauge. It doesn't take much.)

Quoting bikerthai (Reply 208):
One of which could be (pure speculation here) that the battery failed during installation check and they went in and replaced it.

or ... ET_AOP was LN44. Maybe the battery was replaced to reset the 10-year (or whatever) lifetime, since the frame had been sitting around for a while, and either the new installation or the new battery was defective in some way?

Fortunately I don't think that we a.nut contributors are all THAT much smarter than the AAIB investigators...

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: ikramerica
Posted 2013-07-22 15:44:23 and read 12654 times.

Quoting KELPkid (Reply 214):
According to all things 787, ET-AOP was delivered in 2012.

My bad. I had read elsewhere in the thread that it was a recently delivered aircraft.

In that case, it could be a matter of each time it tests, the insulation degrades a little more due to the crimp, and eventually leads to metal on metal on this hot day in London.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: KELPkid
Posted 2013-07-22 15:51:08 and read 12667 times.

Quoting ikramerica (Reply 216):

My bad. I had read elsewhere in the thread that it was a recently delivered aircraft.

Relatively speaking. IIRC, she was the newest Ethiopian bird...  

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: sankaps
Posted 2013-07-22 16:14:34 and read 12569 times.

Quoting ikramerica (Reply 211):
So it might be that yes, it WAS a hot day, for London.

A hot day for London is not a hot day by most standard definitions. 30C is positively mild and would be considered a cool day in Doha, and should not be a factor at all for components and aircraft that operate routinely in MUCH hotter and more humid conditions.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: cornutt
Posted 2013-07-22 16:24:19 and read 12497 times.

Quoting PITingres (Reply 215):
Are the control lines really opto-isolated, does anyone know?

My guess is not... if it were, the switch would need a separate power source. I'm guessing that the lines are protected inside the ELT by running them through resistors that effectively act as fuses. If an external voltage gets imposed on the control line somehow, the resistor burns up and isolates the ELT from the voltage.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: seahawk
Posted 2013-07-22 23:00:06 and read 11704 times.

Quoting Stitch (Reply 206):
If the device is designed to survive under a meter of water for an hour, I would expect it's normally a sealed unit. That being said, if the battery access was not properly sealed, then it does not seem outside the realm of possibility that condensation was able to form inside the battery compartment if the relative humidity was high enough.

Watertight (not very strongly though) is not airtight. If the box of the ELT is a cold spot in the crown area it is possibly humiditiy can built up inside over time. The gaskets are not perfectly impermeable.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: bikerthai
Posted 2013-07-23 10:47:27 and read 10413 times.

Quoting PITingres (Reply 215):
Maybe the battery was replaced to reset the 10-year (or whatever) lifetime, since the frame had been sitting around for a while,

This is absolutely a possibility. There are many back-up batteries on many LRU's that have a shelf life (some not as long as the 10 years) that some customers will insist on fresh ones at deliveries.

bt

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: LTC8K6
Posted 2013-07-23 11:13:38 and read 10276 times.

Perhaps someone was worried about lithium batteries and inspected the ones in the ELT?

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: kanban
Posted 2013-07-23 11:24:32 and read 10235 times.

Maybe some mechanics can answer this.. is checking the ELT part of getting a stored a/c ready for flight a normal procedure?

Wish we had some idea of where the crimped wire was and what crimped it.. say getting caught in the access panel seal and getting torqued to ensure a tight seal?

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: glbltrvlr
Posted 2013-07-23 11:42:03 and read 10235 times.

Quoting kanban (Reply 223):
Wish we had some idea of where the crimped wire was

From AvWeek:

Quote:
According to sources close to the investigation the remnants of the RESCU 406AFN showed evidence of a kink in the wiring which was likely related to its original assembly rather than something that could have occurred during its installation in the airframe.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: LTC8K6
Posted 2013-07-23 11:45:41 and read 10180 times.

A kink?

I thought it was a crimp, as in a crush mark.

I would never describe a pinched or crimped wire as a kinked wire.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Tristarsteve
Posted 2013-07-24 11:49:20 and read 8704 times.

Quoting KELPkid (Reply 214):
The unit is to be tested (or self-tested as the case may be ) once a month in a 5 minute window on the hour (

If an ELT is self tested, how do you know it works?
The only output from the ELT to the aircraft is ELT ON. Is there a readout of the QAR to find out if there was an ELT ON message at the right time?
Does someone listen out to ELT transmissions and record them? I am not criticising, just curious. I work on the line and have never heard of ELT testing. Perhaps it happens at base without my knowledge.Our B787 maint manual just talks about a battery test every 3 years. No mention of monthly testing.
Just seems a bit weird that a box could emit a signal every month all by itself, and someone listens and says it is OK.

I must find someone in the engineering office and ask them.

I was called out by an ELT on an A320 once. The ELT control switch is on the overhead panel, and someone had hit the switch with their head, turning it on. Soon after our maintenance control called to say that the RAF were asking if this A320 was OK, so I went out and turned the ELT off!

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: KELPkid
Posted 2013-07-24 12:06:36 and read 8924 times.

Quoting Tristarsteve (Reply 226):
Does someone listen out to ELT transmissions and record them?

The tower is usually constantly monitoring 121.5, as are serveral aircraft enroute (at least, your *encouraged* to do it...). Can't always free up a radio to tune 121.5   Of course, some newer ELT's don't even transmit on 121.5...only 406 (which is for satellite based SAR coordination).

In the US, if an ELT is heard outside the 5 minute test window, the powers that be will notify the Civil Air Patrol, who will proceed to try and determine the source of the transmission. If it's on the airport, the source is usually found pretty quickly (usually the case-most ELT activations, as you've probably experienced, are accidental   ). Amateur radiio operators in the US also listen for ELT activations, and some automated equipment (like amateur radio VHF repeaters) will automatically report an ELT detection. Very simple triangulation equipment and/or techniques can be used to locate the source of the transmission. Civil Air Patrol aircraft have triangulation receivers on board, which acts like an ADF needle to locate an ELT transmission.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: LTC8K6
Posted 2013-07-24 12:34:33 and read 8795 times.

Quoting Tristarsteve (Reply 226):
If an ELT is self tested, how do you know it works?

Well, there are apparently companies that receive the self test messages for you.

http://www.safelifesystems.com/Default.aspx

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: KC135R
Posted 2013-07-24 18:23:46 and read 8330 times.

Another article with some updated information:

http://seattletimes.com/html/busines...y/2021456975_787firesourcexml.html

Quoting kanban (Reply 223):
Wish we had some idea of where the crimped wire was and what crimped it.. say getting caught in the access panel seal and getting torqued to ensure a tight seal?

In photos of what was left of the device, “You can clearly see the two wires crossed over each other. It’s quite evident the wires show evidence of being smashed,” one source said.

It appears the wires were trapped when the cover was put back on.

Quoting PITingres (Reply 215):
Maybe the battery was replaced to reset the 10-year (or whatever) lifetime

Maybe...
The two sources suggested that Honeywell might have replaced the batteries at some stage before delivery of the jet because the devices sat on the shelf during the years-long 787 program delays.

Perhaps one theory can be put to rest...
There’s no evidence of moisture damaging the batteries, which had been another theory put forward in the press.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: seahawk
Posted 2013-07-24 23:07:18 and read 7754 times.

That is great news for the 787. Human error is unfortunate but no problem for the plane. And this finding explains all actions taken so far. I blame myself for being to scpetical with the 787.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Speedbored
Posted 2013-07-25 00:08:26 and read 7550 times.

Quoting seahawk (Reply 230):
That is great news for the 787. Human error is unfortunate but no problem for the plane. And this finding explains all actions taken so far. I blame myself for being to scpetical with the 787.

Well let's not get too far ahead of ourselves. I agree that it will be good news for the 787 when (and if) it is confirmed by the AAIB that the fire was caused by mis-assembly causing damage to wires in the ELT. [unless, of course, there's something about the way the ELT is installed on the 787 that makes access difficult, making it impossible for technicians to see whether wires are trapped, but I don't want to suggest that is even a remote possibility unless we hear it from the AAIB]

We should keep an open mind on this until we get some officially confirmed information from the AAIB. Let's not forget that, so far, all that the AAIB has really said on the subject is that the fire might have been caused by something related to the ELT. All of this additional information about possible damage to wiring, possibly caused by them being trapped when a cover was replaced, possibly when the batteries were swapped, etc., etc. is still just unsubstantiated rumour from anonymous sources, via journalists.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: bikerthai
Posted 2013-07-25 06:06:06 and read 6951 times.

Quoting Speedbored (Reply 231):
[unless, of course, there's something about the way the ELT is installed on the 787 that makes access difficult, making it impossible for technicians to see whether wires are trapped,

Unlikely, considering:

1) Accessibility for maintenance is always considered when designer locate LRU.
2) Wide bodies in general have more room in the crown to work with (things are not as cramped) unless you have crew rest area, in which case access panels are provided.

The other option, if replacing the battery is too difficult on the airplane, is to take the unit off and replace the battery on the bench.

If they are talking about a 1 hr procedure to replace the battery, I'm guessing it's done on the bench.

bt

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: zeke
Posted 2013-07-25 06:10:39 and read 6926 times.

Quoting bikerthai (Reply 232):
If they are talking about a 1 hr procedure to replace the battery, I'm guessing it's done on the bench.

Or 5 minutes for the physical change, and 55 minutes for the checks and paperwork.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: kanban
Posted 2013-07-25 08:14:42 and read 6528 times.

what is curious is the FAA is only directing the 787's be inspected, yet there are some 5000 units out there on other planes.. if the problem is assembly or maintenance caused, one would think all would be inspected. Or is it just the poor 787 gets no respect so becomes the poster child?

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: Aesma
Posted 2013-07-25 08:46:28 and read 6376 times.

It could be that it's the same person/team that did the replacements on most/all 787s so the most likely affected units would be on the 787.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: robffm2
Posted 2013-07-25 09:04:34 and read 6254 times.

If this is really the same device on 5000 different planes than I don't buy the argument that the batteries had to be changed due to the 787's delays.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: kanban
Posted 2013-07-25 10:03:22 and read 5989 times.

Quoting Aesma (Reply 235):
It could be that it's the same person/team that did the replacements on most/all 787s so the most likely affected units would be on the 787.

If it was internal, it's highly unlikely.. than then there are planes from all manufacturers that have had batteries changed in maintenance facilities all over the globe.. (one commenter indicated his company's internal process required changing them every year).. plus while this plane may have been changed in Addis Abba, the Japanese planes didn't go there for work.

Quoting robffm2 (Reply 236):
If this is really the same device on 5000 different planes than I don't buy the argument that the batteries had to be changed due to the 787's delays.

I would gamble that some customers may include changing all batteries when a plane has been reactivated after even a few months storage. since we haven't seen pictures or schematics, it's all speculation as to what actually occurred. Maybe the batteries were removed at some point to preclude failure.. or maybe there was a low battery alert because of the crimped wire, and all they did was change the battery and didn't look at the wiring...

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: sankaps
Posted 2013-07-25 10:33:34 and read 5856 times.

Quoting kanban (Reply 234):
what is curious is the FAA is only directing the 787's be inspected, yet there are some 5000 units out there on other planes.. if the problem is assembly or maintenance caused, one would think all would be inspected.

Exactly. This is the elephant in the room that so many are trying not to see.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: JoeCanuck
Posted 2013-07-25 11:15:19 and read 5687 times.

Quoting robffm2 (Reply 236):

The batteries are time limited. They must be changed out by a certain date or the ELT automatically loses certification, regardless of the condition of the battery....much like the certification program on fire extinguishers, which have to be inspected and recharged even if they've never been used.

Quoting sankaps (Reply 238):

What elephant...specifically? These devices are made by Honeywell. Boeing did nothing except mount them on their aircraft. We don't know who changed the batteries or even if they were changed.

Maybe they were serviced by Boeing and one of their technitions made the mistake. Maybe they sent them out. That would isolate the cause of the problem. If more 787 ELTs were service by the same people/company/whatever, then checking those would be the smart move.

If the other thousands of ELTs were not serviced by the same people, then there really isn't much cause to force inspections.

So far, no reguatory or investigation agency has indicated there is anything wrong with the 787, in relation to the ELT fire, nor have they critcized the way Boeing has the device mounted.

We have one ELT catching fire and it happened to be on a 787. Bad luck, but that's about all the elephant that seems to be in the room.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: nomadd22
Posted 2013-07-25 11:32:19 and read 5592 times.

Quoting robffm2 (Reply 236):
If this is really the same device on 5000 different planes than I don't buy the argument that the batteries had to be changed due to the 787's delays.

The devices might have an ID programmed into them to associate them with a particular plane. In that case, if a batch of them sat on the shelf for three years because of the delays, it wouldn't be surprising to have the batteries changed out before they were installed.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: bikerthai
Posted 2013-07-25 11:40:35 and read 5574 times.

Quoting nomadd22 (Reply 240):
In that case, if a batch of them sat on the shelf for three years because of the delays, it wouldn't be surprising to have the batteries changed out before they were installed.

Considering how fast the 777 and 737 roll out the door, the only other program that may have had ELT sitting on the shelf for a long time would be the 747-8. But the 747-8 would have had an active 747 line going to consume those on the shelf.

bt

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: PITingres
Posted 2013-07-25 13:35:41 and read 5255 times.

Quoting robffm2 (Reply 236):
If this is really the same device on 5000 different planes than I don't buy the argument that the batteries had to be changed due to the 787's delays.

What would the number of units in service have to do with it? You have a unit sitting in a plane for 3 years and when it finally ships, the customer wants fresh batteries in the thing. Why should they pay for a battery change 3 years early? If you follow the link up-thread to the data sheet on the device, it's very clear that it's designed to swap out a battery clip, not the entire unit. There would be no reason whatsoever to swap an entire unit.

Quoting kanban (Reply 234):
what is curious is the FAA is only directing the 787's be inspected, yet there are some 5000 units out there on other planes.. if the problem is assembly or maintenance caused, one would think all would be inspected.

I don't see any FAA directives on the topic at all. I might not be searching for the right thing, of course; but is there in fact a directive out there about inspecting the ELT's? and, was it issued before or after the wire thing was discovered? (assuming that the info about the mashed wires is in fact correct, and I guess we don't know that officially yet.) If before, the inspection directive might have been a precautionary fishing directive, which might be why it only applied to the 787.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: thunderboltdrgn
Posted 2013-07-25 14:33:17 and read 5063 times.

Quoting PITingres (Reply 242):
What would the number of units in service have to do with it? You have a unit sitting in a plane for 3 years and when it finally ships, the customer wants fresh batteries in the thing. Why should they pay for a battery change 3 years early? If you follow the link up-thread to the data sheet on the device, it's very clear that it's designed to swap out a battery clip, not the entire unit. There would be no reason whatsoever to swap an entire unit.

Maybe rob means that if several aircraft models uses the exact same type of ELT,
then perhaps they have not put them on a shelf for 3 years but rather used them
for the other aircrafts that uses the same model?

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: LTC8K6
Posted 2013-07-25 14:59:23 and read 4927 times.

http://www.faa.gov/news/press_releases/news_story.cfm?newsid=14914

Press Release – ELTs aboard Boeing 787 aircraft

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: robffm2
Posted 2013-07-25 15:13:14 and read 4854 times.

Quoting thunderboltdrgn (Reply 243):
Maybe rob means that if several aircraft models uses the exact same type of ELT,
then perhaps they have not put them on a shelf for 3 years but rather used them
for the other aircrafts that uses the same model?

Exactly what I mean!
  

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: ikramerica
Posted 2013-07-25 16:29:42 and read 4621 times.

Quoting thunderboltdrgn (Reply 243):
Maybe rob means that if several aircraft models uses the exact same type of ELT,
then perhaps they have not put them on a shelf for 3 years but rather used them
for the other aircrafts that uses the same model?

From earlier in the threads I believe I read that this model is ONLY used in the 787, and similar models were used in other aircraft, which led the FAA to recommend temporarily removing them from the 787 but only checking them on other aircraft during the next convenient time. But that might have been speculation on the part of the poster.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: KC135R
Posted 2013-07-25 16:54:28 and read 4514 times.

Regarding the ELT and other aircraft, it looks like other aircraft with this ELT might be looked at yet:

U.S. aviation regulators ordered inspections of emergency locator transmitters linked to a July 12 fire on a Boeing Co. (BA) 787 and said they may take more action affecting thousands of identical beacons on other models.

“We acknowledge that ELTs are installed on various other aircraft,” the FAA said in the order. “Therefore, continued investigation is required. Once final action has been identified, we might consider further rulemaking.”

Source:
http://www.bloomberg.com/news/2013-0...io-beacons-linked-to-787-fire.html



[Edited 2013-07-25 16:55:54]

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: PITingres
Posted 2013-07-25 17:22:13 and read 4438 times.

Quoting thunderboltdrgn (Reply 243):
Maybe rob means that if several aircraft models uses the exact same type of ELT,
then perhaps they have not put them on a shelf for 3 years but rather used them
for the other aircrafts that uses the same model?

Well, OK, that makes at least a little bit of sense now.

On the other hand, even if the ELT model is not unique to the 787 (I don't know either way), I bet the paperwork would be easier if they just left the installed units on the early build 787's without attempting to swap. An ELT swap looks to be at least a bit more work than a battery swap, and it would be just one more thing to deal with at change incorporation time. The price of 30 or 40 battery packs would not reach the inconvenience and exposure cost, I think.

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: sankaps
Posted 2013-07-25 17:22:26 and read 4437 times.

Quoting JoeCanuck (Reply 239):
What elephant...specifically? These devices are made by Honeywell. Boeing did nothing except mount them on their aircraft.

The elephant specifically is the fact that currently only the ELTs installed on 787s are the focus of investigation.

Quoting ikramerica (Reply 246):
From earlier in the threads I believe I read that this model is ONLY used in the 787

If that is proven to be the case, then the 787-only investigation may make sense. Does anyone know if the 787 ELT is not exactly the same model / design / variant as the rest of the 5,000? And if so, what is different about them?

Topic: RE: ET 787 On Fire At Heathrow Part 6
Username: moderators
Posted 2013-07-25 17:35:32 and read 4404 times.

Due to length, here is part 7: ET 787 On Fire At Heathrow Part 7 (by moderators Jul 25 2013 in Civil Aviation)


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