Shenzhen
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 4:58 am

Quoting Shenzhen (Reply 195):
Quoting cornutt (Reply 197):
So the absolute minimum for getting all delivered 787s back into service appears to be about five weeks from when the solution is found. And that's assuming an awful lot of people are working day and night.

These things wouldn't be done in series. I would say that a large number of the batteries and maybe the chargers have already been removed from airplanes and undergone testing. Results would be required as part of the risk mitigation.

Cheers
 
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Stitch
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 4:58 am

Quoting tdscanuck (Reply 181):
But a flaming battery was a foreseen failure. I'm confused why this keeps coming up.

Because it's sensationalist.

Quoting YVRLTN (Reply 200):
I dont know the answer, but from the photo from Shamu330 in post 207 in thread 3, as well as the green substance there does seems to be some brown scorch marks too on the fuselage. That suggests it was pretty hot temperature wise (despite hitting the cold air outside) or it was flammable enough to interact with the fuselage to cause scorching.

The electrolyte is brown in color. So what you are seeing is electrolyte that was ejected from an outflow valve and coated the fuselage as it was caught in the airflow over the fuselage.

It is not scorching caused by exposure to high temperatures.
 
spacecadet
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 5:02 am

Quoting ikramerica (Reply 192):
Why wasn't the 747 grounded after TWA 800?

A better question would be, why wasn't it grounded beforehand? 230 more people (give or take) would be alive right now. The answer is that the FAA was apparently not aware of the danger posed by empty fuel tanks during hot weather, despite several earlier incidents. (After the accident, as with most other accidents, airworthiness directives were issued as the cause was narrowed down that made a grounding unnecessary. By the time the systemic problem was recognized, workarounds were already in place.)

Luckily, they are not making the same mistake with lithium ion batteries. They gave Boeing the benefit of the doubt once, and it got them one fire at the gate and one emergency landing with an evac using slides. So far.

I'm not sure that some of you guys realize that your arguments boil down to putting economic concerns over human lives. No plane should be flying if it's flying with an unknown level of safety. No amount of money is worth it.
I'm tired of being a wanna-be league bowler. I wanna be a league bowler!
 
XT6Wagon
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 5:23 am

Quoting spacecadet (Reply 205):
I'm not sure that some of you guys realize that your arguments boil down to putting economic concerns over human lives

Um, You HAVE to make economic vs safety judgements or there is no point in having the industry. The Airline industry is the safest form of transport on the planet, so clearly they are quite agressive in spending money to save lives, but there is a point where you make the world less safe by spending too much on safety. How much money would you be willing to spend to have 10% less people die in aircraft each year? I don't know the real numbers but its a pretty ugly amount of money to do so. So lets say 50% higher ticket prices to kill off a crash a decade. What do you think that would do to the industry? Too much and you start killing people when you push them off into deadly cars, buses, trains, bikes, and even walking since all of these activities are far less safe than planes are TODAY.
 
rcair1
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 5:47 am

Let the flame fest begin!

So - I got really tired of reading patents today and so I started looking for concrete new data on Li-Ion battery fire danger and suppression techniques. I even spent a fair amount of time reading about "bricking" your Telsa.

I've discovered some errors in what has been posted here, including errors that I made.

To be clear - the information I provided was based on training I received in an alternative fuels class I took about 4 years ago - and it seems like the understanding is evolving.

First - the biggest source of misunderstanding is confusing Lithium and Li-Ion battery chemistry and the approaches to fighting a fire in both cases.

In Lithium battery fires - these are non-rechargable Li Batteries - known as primary batteries - there is significant metallic Lithium. This is a true metal class fire and requires class D extinguishing agents. Conventional extinguishers - ABC as well as Halon, and most especially water - do not work.
-> My training was focused on this - and either I missed the following, or it was not covered.

In Lithium-Ion rechargeable batteries - secondary batteries - there is little metallic Lithium. You can use water or class ABC extinguishing agents - though the efficacy of them is unproven. The primary fire hazard for a Li-Ion battery is 2 fold - heat due to thermal runaway and flammable electrolyte/vent gas. The big difference - which I have just learned - is that the electrolyte in a Li-Ion battery is more flammable that the electrolyte in other batteries (like NiCad or NiMH) because it is not water base. Those other electrolytes pose much higher corrosion and toxicity concerns, but lower fire concerns.

Tests seem to indicate that conventional techniques, if they could be applied, would be effective in extinguishing the flame - however, the danger posed by re-kindle is major.
For instance, Halon 1301 is shown to be effective extinguishing the flame (electrolyte/gas), but not cooling the battery. If you use Halon, you will likely face re-kindle. An effective suppression would need to persist - to remain on the fire long enough to extinguish re-kindles long enough for thermal runaway to terminate. Water is effective in cooling, except that the design of the battery makes it difficult/impossible to apply well enough to overcome the heating of a thermal runaway.

It is interesting to note the 2 methods discussed for aircrews to deal with runaway fires in consumer batteries (laptops) are to 1) douse them repeatedly with water or 2) put them in a containment bag. The containment bag is designed to contain the heat long enough for runaway to terminate and the fire to go out. No effort is made to contain vent gasses in these containment bags. The reports I read seemed to indicate the containment bag was a better approach - it was surer.

It is also unclear if "spreading" the electrolyte by washing it around with water is a concern.

So - the primary issue extinguishing a Li-Ion battery fire is that, while you can potentially extinguish the 'flame' you cannot effectively cool a battery in thermal runaway well enough to prevent re-kindle of either the electrolyte or gasses being expelled. A Halon extinguishing system in the EE bay would be ineffective - it may put out flames (if they are outside the containment), but would not cool the battery. Thermal runaway would continue and re-kindle would be likely.

BTW - the data I could find so far indicates that the flammability limit LFL to UFL for vented gasses is small. LFL is the concentration in air below which the gas is non-flammable (too lean) and UFL is the concentration above which it is not flammable (too rich). A narrow flammability range means that an effective control method is to either concentrate or disperse the gas. The latter is obviously the better choice. Therefore - effective and positive ventilation is important.

One of the better references I've been studying is research performed by the Fire Protection Research Foundation - funded by the NFPA (National Fire Protection Association) - an organization I work with a lot.

The report I reference is located at the link below and was dated July 2011. I might refer you to Chapter 6 (page 84) and beyond.

The obvious question one may ask is does this change my opinion on the situation the 787 and Boeing face. The answer I have is - I'm sure - not going to satisfy some. Simply stated - I don't know yet - I need more data.

It seems that containment and venting (if those are not contradictory terms) are still the best approach based on the data I have seen. Vent the gas to keep it below LFL. Contain the fire so it says in the 'box'.

I do have a concern about the leaked electrolyte. Based on the new knowledge I spent the afternoon gaining (not from a.net by the way), my level of concern is increased. If it is flammable - and it appears it may be (since we do not know the exact composition of the Yuasa batteries, I can't say for sure) it represents a hazard. Is it a hazard that can be managed by placing it in a location where, if ignited, it will consume itself and burn out without the fire extending - then - no. If it the fire could extend - then yes. I would caution you that even the NFPA report I'm citing states that Li and Li-Ion battery chemistry varies dramatically and they are careful not to point out that testing all the types of chemistry is beyond the scope of their research.

These are questions that need to be reviewed and answered. Of course - that is exactly what Boeing and the FAA is doing.
Link to NFPA report http://www.nfpa.org/assets/files/pdf...ch/rflithiumionbatterieshazard.pdf

My apologies for misinforming that re-chargeable Li-Ion secondary batteries require Class D.
rcair1
 
nm2582
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 6:34 am

Quoting bellancacf (Reply 172):

to nm2582 at 168: The Tesla roadster has, I read elsewhere, 6831 cells in its battery. What on earth does the balancing circuit look like? Is each cell really monitored individually? There's got to be a trick in there somewhere . . . But then, if the 787 has 8 cells to be handled by each charger (there are 2 chargers, aren't there?), the comparative simplicity ought to make keeping these cells balanced a piece of cake. And if the cells are too large, well, make them smaller and do whatever it is that Tesla's doing.  

Tesla has very different requirements for their battery than does Boeing. The Tesla battery stores a LOT more energy than does the 787 battery and has a very different purpose. This PDF describes it way better than anything I could do:

http://www.teslamotors.com/display_data/TeslaRoadsterBatterySystem.pdf

The Tesla battery is subdivided down to 11 sub-assemblies (called sheets); each sheet has it's own electronics and circuitry to monitor the individual cells. This subdivides the monitoring problem.

I do not know the internal electrical construction of the Tesla battery, so I am NOT speaking definitively here. It is very possible that Tesla parallels many cells together and then build series chains out of these paralleled groups. This would further reduce the amount of monitoring/balancing needed - when you have cells wired in parallel (+ to + and - to -) they by definition are at the same identical voltage. You could have dozens of these cells in parallel together, and you would only need to monitor one single voltage to know the voltage of all cells in the group. Then you string these parallel groups together in series to get your voltage requirement (over 300V on the tesla). Parallel groups have their own special failure modes (if a single cell fails shorted, the other cells in the parallel group short through the failed cell) but the Tesla PDF says each individual cell is protected by two fuses.
 
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seahawk
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 7:21 am

I think the problem is that if we combine the 2 events, there is a theoretical possibility for a major problem in the 787.

In first failure the containment worked, the battery burned itself out, the gases were vented - more or less as designed I would say.
In the second case the electrolytes did not ignite, only smoke, but left the containment box and spilled into the fuselage. Nothing major again as the electrolytes are not that dangerous either.

It becomes critical if you imagine a leaking battery catching fire and this has to be considered possible at the moment.

The other problem is that those vent gases are considered possibly toxic. So they must not reach the cabin. The exact danger level and exact reactions to the occurence of such vent gases is still under discussion afaik though.

And if you think it is unreasonable to be concerned a failure rate of 1:200000 led to a recall of 6 million laptop computers from Dell and Apple.

Here is a link (unfortunately mostly in German on testing such batteriesand the possible risks depending on failure modes): http://www.basytec.de/Literatur/2010_Sicherheit_Testen.pdf
 
nm2582
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 7:39 am

I am sure tests like these are already being done, but it would be really interesting to know how the 787 handles these situations... (this is by no means an exhaustive lists of tests I'd want to try, just a few off the top of my head!)

Charge an entire battery to 90% capacity. Remove a single cell from the battery and discharge it to 15%. Add it back to the battery. Install the battery in the main ship battery location, and power the 787 up off this battery. What happens when the 15% charged cell gets to it's minimum safe voltage (which it will do quickly)? Does it continue to discharge past the minimum safe voltage? Once the battery is consumed/discharged, start the APU. If the main ship battery went below minimum safe voltage, does the charger still charge the battery (the cell is now damaged and unsafe, so charging is unwise)? If over-discharge was prevented, does the charger properly re-charge the entire battery to a balanced, safe state?

Charge an entire battery to 15% of capacity. Remove a single cell and charge it to 90% capacity. Add the cell back to the battery. Install the battery to the main ship battery location, start the APU, and allow the main ship battery to charge. Does the single high cell ever exceed it's maximum safe voltage? Does the battery charge up to a balanced, safe state?

While somewhat drastic, these kinds of tests would quickly uncover any limitations, flaws, missing protections, etc. in the charging system.

It would also be interesting to repeat these tests on ground power instead of APU power, and also with the "doctored" battery in the APU location instead of main ship battery.





[Edited 2013-01-22 23:42:41]

[Edited 2013-01-22 23:44:28]
 
RickNRoll
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 8:23 am

Quoting seahawk (Reply 206):
In the second case the electrolytes did not ignite, only smoke, but left the containment box and spilled into the fuselage. Nothing major again as the electrolytes are not that dangerous either.

They are apparently flammable.
 
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N14AZ
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 8:52 am

Well, since this thread is discussing all kind of things except for the current investigations I feel free to post my theory:

Quoting ADent (Reply 102):
Quoting flood (Reply 48):
Thanks for the link. I had previously only seen a photo of the damaged battery when it had already been removed... there's another photo of it still installed on page 3 of the thread.
http://i337.photobucket.com/albums/n385/motidog/ANAbatt0.jpg

I think FAA should investigate if a certain David was on board of the two flights.
http://images.wikia.com/alienanthology/images/7/78/Prometheus_black_liquid.jpg
Source: http://images.wikia.com/alienantholo...s/7/78/Prometheus_black_liquid.jpg

But seriously, any news about the investigations?
 
KC135Hydraulics
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 9:27 am

How's this for containment?

KC-135 battery arrangement:

MSgt, USAF
KC-135R / C-17A Pneudraulic Systems Mechanic Supervisor
 
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seahawk
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 9:29 am

What type of battery?
 
UALWN
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 9:32 am

Quoting Shenzhen (Reply 179):
When the A330 went down, nobody knew why until sometime after the event. Why not ground the fleet, after all, safety is number one, no?

The fleet wasn't grounded but the Thales pitot tubes had to changed quickly. One could argue that this should have been mandated way before, since there were several reports of the Thales tubes freezing up during cruise.

Quoting YVRLTN (Reply 197):
AFAIK there has been no need to use these batteries in commercial service? Apart from being a smaller capacity to start with, it seems this battery in the 787 gets a far bigger work out.

Exactly. More arguments to stop bringing up the A380 into this discussion.
AT7/111/146/Avro/CRJ/CR9/EMB/ERJ/E75/F50/100/L15/DC9/D10/M8X/717/727/737/747/757/767/777/787/AB6/310/32X/330/340/350/380
 
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Faro
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 9:55 am

It seems media focus is shifting to the FAA's role in approving Boeing's decision to install Li-Ion batteries back in 2007:

Quote:
In 2007, U.S. regulators cleared Boeing's use of a highly flammable battery in the 787 Dreamliner, deciding it was safe to let the lithium-ion battery burn out if it caught fire mid-air as long as the flames were contained, and smoke and fumes vented properly, according to documents reviewed by Reuters.

http://www.reuters.com/article/2013/...eing-787-faa-idUSBRE90M04620130123

Very difficult to see where we're headed at the present time with the grounding IMHO...


Faro
The chalice not my son
 
s5daw
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 10:00 am

Quoting faro (Reply 213):
nd smoke and fumes vented properly

Apparently at least the fumes part was problematic in the ANA incident...
 
cmf
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 12:13 pm

Quoting XT6Wagon (Reply 203):
The Airline industry is the safest form of transport on the planet

Actually it is one of the most dangerous, only bikes and motorcycles are more dangerous. It is some 30 times more dangerous than using a bus. Three times more dangerous than using a car. All of this when you switch from the passenger km to passenger trip. Statistics can be your friend, or your enemy  
Don’t repeat earlier generations mistakes. Learn history for a better future.
 
liquidair
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 1:12 pm

Quoting tdscanuck (Reply 171):

Eh?

I'm not advocating that a fail safe design shouldn't be incorporated- of course you need some sort of containment in the event of said failure.

And, as you and others have so intelligently pointed out, there are many flammable materials on a plane, not least the jet fuel. thanks for educating me.

you want to know what I can't understand keeps coming up? The fact that so many seem to be trivialising what is an extremely worrying series of events. You may insist that these fires were foreseen- and they were not dangerous- I will again reiterate that accidents happen when events move beyond our control, however unlikely it is that they occur.

I mean, are we really trying to debate over the fact that a flaming battery should be de rigeur? That technological advancement with the 787 should inherently pose a threat to it's passengers?

I'm going to take the view that beyond the patronising, sometimes vitriolic responses, there is actually a valid discussion going on.

[Edited 2013-01-23 05:13:43]
trying to stop my gaseous viscosity go liquid
 
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Aesma
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 1:29 pm

Quoting par13del (Reply 175):
This one makes absolutely no sense, we all know that the politicians in the USA are in Boeing's back pocket, see the illegal subsidies and the bogus tanker contract, why would they do this, is there no loyalty?

The US has enough powerful politicians to have some in Airbus pockets too. But here if I wanted to see a political conspiracy I would rather see it as a ploy for/against Obama. Of course the fact that Li-Ion batteries were designed in the 787 years before he took power makes the conspiracy far fetched...

Quoting bellancacf (Reply 186):
Coolant is pumped continuously through the ESS both when the car is running and when the car is turned off if the pack retains more than a 90% charge. The coolant pump draws 146 watts.[41][108][109][110]

Wow, that's an impressive pump right there. I wonder if it's really always drawing so much or if it has a wide range of speeds. By comparison the pump I'm using to cool about 700W of heat in my computer is at 18W. Then a couple of watts for the fans on the radiators.
New Technology is the name we give to stuff that doesn't work yet. Douglas Adams
 
dtw2hyd
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 1:40 pm

Quoting par13del (Reply 175):
This one makes absolutely no sense, we all know that the politicians in the USA are in Boeing's back pocket, see the illegal subsidies and the bogus tanker contract, why would they do this, is there no loyalty?

To the contrary, Boeing rubbed the current administration's National Labor Relations Board wrong way when Boeing tried to open Charleston,SC plant. So actually administration doing a huge favor standing next to Boeing on this matter.
 
Kaiarahi
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 1:52 pm

Quoting prebennorholm (Reply 185):
Except maybe that customers demand Li-Ion free planes,

Which would require banning many (most?) electronic devices.
Empty vessels make the most noise.
 
rcair1
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 1:54 pm

Quoting faro (Reply 213):
It seems media focus is shifting to the FAA's role in approving Boeing's decision to install Li-Ion batteries back in 2007:

The media follows politicians. Politicians - particularly the US Congress and Senate are feeling rather impotent - so this is a chance for them to get on the stage. That is all.
rcair1
 
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par13del
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 2:04 pm

Apologies to all, it was a comment in jest, should have used the smiley, point was that a few months ago everything was the US government covering Boeing, funnelling billions in illegal aid, WTO agreeing, etc etc etc, now that same "bought" government is investigating Boeing?

Quoting DTW2HYD (Reply 218):
Boeing rubbed the current administration's National Labor Relations Board wrong way when Boeing tried to open Charleston,SC plant. So actually administration doing a huge favor standing next to Boeing on this matter

And the current administration is the same as was there before, including all the "civil servants" who are not compelled to resign their jobs because the administration is the same.
Actually Boeing and most major US companies who have been out-sourcing jobs outside the USA have been rubbing those politicians the wrong way for years, the difference now is that more of them have positions of power and influence to act on their convictions.

Nothing new on the investigation front, at least substantive, so will continue waiting, however, we are rapidly getting to a point where something has to happen, the status quo cannot continue for another week or so.
By that I mean, airlines, investors, regulators, Boeing etc. will need some guidance pretty soon, some time lines have to be provided, even if they are rough estimates.
Pax are still booking flights, airlines need to source replacement a/c, crews and a/c picking up the slack will need some downtime, ultimately, long term planning has to take place and for that to happen you need a starting base.
The NTSB is safety focused, the FAA is more industry focused, so as soon as the NTSB has something definitive in terms of where the problem lies, I expect the FAA to start working on some advisory to Boeing and the airlines on what they can expect.
 
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Stitch
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 2:26 pm

I wonder if Yuasa can do a materials change in the battery to a cathode chemistry more stable than the lithium cobalt oxide used in the 787's batteries (which is more susceptible to thermal runaway in cases of abuse such as high temperature operation (>130ºC) or overcharging).

Lithium nickel cobalt aluminum oxide and lithium nickel manganese cobalt are both more stable and safer cathode chemistries that were not available when the 787 was being designed (lithium nickel manganese cobalt, for example, was created in 2008).

Lithium iron phosphate is safer still, and evidently would only require one additional cell to provide the same power density as the current battery pack, which might allow it to fit in the current bay location.
 
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Aesma
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 2:32 pm

Someone has mentioned France launching an investigation, can that be backed up, because I don't think it's true ?

The BEA is involved into the NTSB investigation, I reported about that, but it's as it should be since a French company is involved in the investigation. No French politician has to intervene, there is no National Assembly or Senate committee or things like that. The 787 has not even made the headlines here, since we just started a war, at best it had a corner of newspapers' front pages.
New Technology is the name we give to stuff that doesn't work yet. Douglas Adams
 
abba
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 2:58 pm

Quoting tdscanuck (Reply 171):
Yes. But individual components on aircraft fail quite regularly; that's why no single failure is allowed to threaten safe flight and landing, regardless of how likely the failure is. Interactions are dealt with on a probability basis. The big open question, in this case, is if battery fires are more likely than expected, how does that interact with all the other systems. If a battery fire, by itself, could threaten safe flight of the aircraft then it would never have been certified in the first place.

Quoting tdscanuck (Reply 178):
The issue with the current problem is that it might not comply with regulations that require the probability of a catastrophic event due to foreseeable *combinations* of failures must be extremely remote.
Thanks Tom. This is a absolutely brilliant way of explaining the issue in a way that even I understand. As so often before your posts are highly appreciated.

[Edited 2013-01-23 07:02:07]
 
sankaps
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 3:23 pm

Quoting ikramerica (Reply 189):
Why wasn't the 747 grounded after TWA 800? Or after the side ripped off over the Pacific? Why wasn't the A330 grounded after the AF hull loss? Why wasn't the A380 grounded while the engine issue was solved? Why were check and go good enough for those cases but not now?

Why wasn't the 787 grounded after the JAL incident? Because it was just ONE incident. If a second similar one were to have happened within days on the 747 or 330 or the 380, then perhaps the question would be relevant.
 
nm2582
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 3:37 pm

Quoting Stitch (Reply 222):

Lithium iron phosphate is safer still, and evidently would only require one additional cell to provide the same power density as the current battery pack, which might allow it to fit in the current bay location.

If I were in charge of working on the battery (which I'm not - I'm a software guy by trade, and not in the aviation industry or anything connected to it) then LiFe would definitely be at or near the top of my list, it's a very stable chemistry.

With that said, a chemistry switch (in my opinion) isn't the big issue here, the big issue is figuring out what is happening to the battery which is causing failures. Lithium ion cells are actually pretty benign (relatively speaking) until they experience conditions they don't like (overcharge, overdischarge, too high of a charge current, over temperature, under temperature, too high of a load, physical damage); so the real key is to determine when and why they experienced conditions which lead to them failing. The battery and electrical system should have safeguards to protect the cells from ever experiencing these conditions. The presumption is that (after two battery failures) the cells are experiencing conditions which they should not ever experience.

If you just switch chemistry, it's entirely possible that whatever caused the lithium ion cells to fail, will cause damage to or keep occurring to the new cells. Switching chemistry is kind of like putting seat belts and air bags in cars: it's a good idea, and it makes accidents safer and more survivable; BUT it doesn't prevent the accident. They need to understand why the accidents are occurring and prevent them.
 
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PITingres
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 3:48 pm

Quoting liquidair (Reply 216):
you want to know what I can't understand keeps coming up? The fact that so many seem to be trivialising what is an extremely worrying series of events.

I suppose I shouldn't feed the trolls, but ...

I don't understand why you and others seem to think that some posters are trivializing the situation. Just because someone posts factual information about the limited extend of the actual damage does not mean that they are trivializing anything. Every poster demonstrating any actual knowledge about the events, the airframe, or the response has said that the situation is serious and undesirable. That is not the same thing as saying the the planes are going to fall out of the sky in flames, which is what way too many agitators and trolls here have been saying. Disagreement with trolling and hyperbole is not the slightest bit the same as trivializing the incidents in any way.

Maybe you'd like to cite some of the "so many" posts that trivialize the situation? Because I don't see them.
Fly, you fools! Fly!
 
TheSultanOfWing
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 4:02 pm

Just to get practical here for a moment:

Any info on what airframes are being checked physically?
Did Boeing send staff to NRT, ORD, DOH, SCL etc to check each and every plane, or is it just the batteries that are being dispatched and examined?


FH
I feel like the A318 at times: I am probably worth more parted out than as a whole.
 
AeroWesty
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 4:07 pm

Quoting PITingres (Reply 227):
Disagreement with trolling and hyperbole is not the slightest bit the same as trivializing the incidents in any way.

+1. One of the best lines in this thread. I'm amazed and appreciative of the patience and continued measured and intelligent responses from those with direct technical knowledge here, who take vast amounts of their personal time to educate us regarding the problems faced, plus the process of how these problems are worked through, without resorting to hyperbole and ad hominems in their replies.
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alfablue
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 4:10 pm

http://www.reuters.com/article/2013/...eing-787-faa-idUSBRE90M04620130123

Quote:
FAA rules do not cover lithium batteries, so the agency in 2007 set nine "special conditions" Boeing had to meet to ensure their safety. A year earlier, the FAA had set similar conditions for Airbus. Special conditions are commonly used to cover new technology for which rules have not yet been written.

In both cases, the Air Line Pilots Association International, the world's largest pilot union, said airplane fire is so dangerous that the FAA should require cabin crew to have fire extinguishers and training to put out a lithium-ion battery fire. "A fire from these devices, in any situation, is unacceptable," the union said, during the 787 approval process.

The FAA said it chose not to require special fire extinguishers and training because of the four redundant systems already in the Boeing system to prevent the battery from catching fire.

The ALPA said on Tuesday it is monitoring the investigation into the 787 battery incidents, but declined to comment while the probe is going on.

"It goes back to why this was approved in the first place," said Hidetake Sakuma, an aviation safety consultant and a former safety manager at Japan Airlines Co Ltd.

"Of course there were people asking whether this was really safe, but they (the FAA) approved it and the Japanese airlines never questioned it."


So in above article I see two important pieces of info:

The FAA said....prevent the battery from catching fire.

ALPA says: "A fire from these devices, in any situation, is unacceptable,"


Below is the link to the special conditions (again) and you can see that point one is the containment, which is currently under investigation with unknown outcome. Point two however is violated (twice now). I think the NTSB will come to a conclusion that there was a fire (contained or not) and it will be assessed if point 1 of the special condition was met - however point 2 was violated and led to the safety review followed by the grounding after the second violation. So IMHO I think they thought it could have been bad luck or a manufacturing fault. Now we reach the stage where the whole adaptation is being questioned. The containment might have just worked as designed - the problem is that point 2 of the special condition is violated.

http://rgl.faa.gov/Regulatory_and_Gu...3ae59862572cd00701404!OpenDocument


(1) Safe cell temperatures and pressures must be maintained during any foreseeable charging or discharging condition and during any failure of the charging or battery monitoring system not shown to be extremely remote. The lithium ion battery installation must preclude explosion in the event of those failures.

(2) Design of the lithium ion batteries must preclude the occurrence of self-sustaining, uncontrolled increases in temperature or pressure.



Preclude synonyms: avert, cease, check, debar, deter, discontinue, exclude, forestall, forfend, hinder, impede, interrupt, make impracticable, obviate, prevent, prohibit, put a stop to, quit, restrain, rule out, stave off, stop, ward


There was a special condition which was violated and another is under investigation (containment). Both batteries have been ruled out as overcharged now. I said in an above post that regulations can change. Here is another quote doubting the decision to allow those batteries via a special condition - if the FAA takes back the special condition (which is not fulfilled anyways) the batteries have to be exchanged and replaced by another technology, which means drawing board, development, new software, testing, certification and many many month of grounding.

http://www.reuters.com/article/2013/...-787-hearing-idUSBRE90M00220130123


Quote:
Problems with the 787's lithium-ion battery have sparked questions about why the FAA in 2007 granted Boeing a "special condition" to allow use of the batteries on the plane, despite the fact that they are highly flammable and hard to extinguish if they catch fire.

Boeing designed a special system that was supposed to contain any such fire and vent toxic gasses outside the plane, but the two recent incidents have raised questions about whether that was a good decision.


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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 4:16 pm

Quoting nm2582 (Reply 226):
With that said, a chemistry switch (in my opinion) isn't the big issue here, the big issue is figuring out what is happening to the battery which is causing failures. Lithium ion cells are actually pretty benign (relatively speaking) until they experience conditions they don't like (overcharge, overdischarge, too high of a charge current, over temperature, under temperature, too high of a load, physical damage);

Forgive me if I am repeating previously posted information, but these threads are long.

With regards to the above, I recall that the FDR didn't record an over voltage. Does it record current flow in and/or out? Combined current flow in (charging) and out (powering the APU or other load)?

There is also the possibility (and I don't know this) that the instrumentation might not adequately convey an overvoltage event, what resolution in time are these voltage readings stored?
 
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 4:23 pm

Quoting PITingres (Reply 227):

If you regard my opinions as trolling, then you're free not to read them.

I think that in reality, tone is often lost when writing- and absolutism comes across more than it would verbally.

To my mind, whilst I understand the fact that the system have been designed to withstand failure, it's still just not acceptable to employ this technology if this rate of failure occurs.

I've never said that it's an apocalyptic scenario of planes falling out of the sky- I've merely stated that the risk of these fires is a risk too many... And in my all encompassing ignorance and deficiency, I consider this technology too high a risk. Now whether it's the battery or the architecture at fault, I don't know. But it's worrying, and therefore I consider the 787 currently unreliable. As do the FAA apparently.

it's a bit like the risk of surgery- sure, the surgeon knows it is safe, that operation has been performed a million times without any mortality- but I was still apprehensive about taking my tonsils out last year- because things can and do happen.

Now, if you are going to resort to calling me a troller, go ahead- it's just childish. It's that kind of mentality that resorts to hand throwing in bars. Primitive and sad.
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Stitch
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 4:41 pm

Quoting alfablue (Reply 230):
In both cases, the Air Line Pilots Association International, the world's largest pilot union, said airplane fire is so dangerous that the FAA should require cabin crew to have fire extinguishers and training to put out a lithium-ion battery fire. "A fire from these devices, in any situation, is unacceptable," the union said, during the 787 approval process.

Lithium-Ion fires are Class D events. The most effective way to fight such a fire is to use a dry powder extinguisher, which smothers and acts as a heat sink to dissipate heat.

Copper powder is the preferred agent to use against lithium fires as it forms a copper-lithium alloy on the surface which is non-combustible and cuts off the oxygen supply. However, I am not sure how good of an idea it is to spray copper powder around electrical equipment.

Dry graphite also works, but is not as effective as copper powder. Again, not sure how good of an idea it is to have that around electrical equipment, either.

[Edited 2013-01-23 08:42:15]
 
tarheelwings
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 4:42 pm

Quoting liquidair (Reply 232):
Now, if you are going to resort to calling me a troller, go ahead- it's just childish. It's that kind of mentality that resorts to hand throwing in bars. Primitive and sad.

His point still stands, doesn't it?

You were the one making the following statement:

Quoting liquidair (Reply 216):
you want to know what I can't understand keeps coming up? The fact that so many seem to be trivialising what is an extremely worrying series of events.

And he is simply asking:

Quoting PITingres (Reply 227):
Maybe you'd like to cite some of the "so many" posts that trivialize the situation? Because I don't see them.
 
Kaiarahi
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 4:56 pm

Quoting alfablue (Reply 230):
Point two however is violated (twice now).

Not necessarily. It says:

Quoting alfablue (Reply 230):
(2) Design of the lithium ion batteries must preclude the occurrence of self-sustaining, uncontrolled increases in temperature or pressure.

If it's a manufacturing defect, para 2 is not violated.

Quoting nm2582 (Reply 226):
(overcharge, overdischarge, too high of a charge current, over temperature, under temperature, too high of a load, physical damage)

Or an internal short resulting from a production defect.
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liquidair
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 5:02 pm

Quoting tarheelwings (Reply 234):

If you read my whole post, and actually understood it, you'd notice that I'm saying that at times written words come across as absolutism whereas perhaps verbally they would not.

I'll simplify; interpretation of some posts might not be that intended- but it can seem like that.

So no, that point does not stand. And I certainly won't be resorting to name calling (troll) when dealing with different opinions.

The technical explanations can go on until the cows come home- but the point that fire is unacceptable cannot be debated, in my view.

see

Quoting alfablue (Reply 230):
In both cases, the Air Line Pilots Association International, the world's largest pilot union, said airplane fire is so dangerous that the FAA should require cabin crew to have fire extinguishers and training to put out a lithium-ion battery fire. "A fire from these devices, in any situation, is unacceptable," the union said, during the 787 approval process.


[Edited 2013-01-23 09:04:42]
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seabosdca
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 5:07 pm

Quoting AeroWesty (Reply 229):
I'm amazed and appreciative of the patience and continued measured and intelligent responses from those with direct technical knowledge here, who take vast amounts of their personal time to educate us regarding the problems faced, plus the process of how these problems are worked through, without resorting to hyperbole and ad hominems in their replies.

Said it better than I could have.

Panic helps solve nothing in this sort of situation. Dispassionate analysis, on the other hand, will eventually find you causes of and solutions to hazards like this. Insisting on accurate rather than sensational descriptions is far from "trivializing."

[Edited 2013-01-23 09:08:16]
 
Cubsrule
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 5:14 pm

Quoting liquidair (Reply 236):
The technical explanations can go on until the cows come home- but the point that fire is unacceptable cannot be debated, in my view.

Well, yes, it certainly can be. Fire is an acceptable risk in engines, for instance, because it's unavoidable and we have good ways of mitigating it. Engine fires happen on a fairly regular, if not routine, basis.
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 5:19 pm

Quoting Stitch (Reply 233):
Lithium-Ion fires are Class D events. The most effective way to fight such a fire is to use a dry powder extinguisher, which smothers and acts as a heat sink to dissipate heat.

Stitch - I'm correcting you here because you (probably) got this information from me and it is incorrect.
See my long post about that in this thread from this morning.
I believe it is my responsibility to correct bad information from me.

Lithium battery fires are class D. Lithium-Ion battery fires are typically not class D. There is little metallic Lithium in them.

This was my error - based on training that was, apparently, outdated. I spent several hours researching current approaches based on research at NFPA and Sandia and, to my chagrin, discovered my error.

That said - there is no piratical and approved extinguishing method to be used that would work in the environment in question and it appears containment is still the best approach for a number of reasons. This is the recommend approach for Li-Ion 16850 based fires in cabin - use a containment bag that keeps the heat in and vents the gasses till the thermal runaway terminates and the fire goes out.

In the reports I cite - there are specific "gaps" highlighted and one of this gaps is in extinguishing approaches. Remember - this report is from a fire fighting standpoint - not an aircraft design standpoint.

The report is only 126 pages long - should be a quick read for anybody who cares. Of course, unfortunately, many will pull out of context data out of it and use to create a picture of conflagration whenever you look cross eyed at a battery - Bob
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 5:23 pm

Oh my god it's so difficult to sift through what's actually factual.

I clicked the SD button for this whole thread because I don't have the time to sit here and sd all the trolls and arguments.


But for the sake of news this may have been posted, I have no idea because its difficult to weed through this:

Yomiuri, USA Today, and Japan Today all saying that, like the JL frame, the NH plane at TAK did not suffer an over charge. Therefore it's something inherently wrong with the lithium ion batteries themselves.

At this point in my opinion, we can forget any 787 flights for the next month. Yuasa is now in the hot seat and all involved in the Li ion batteries at Yuasa are in deep sh*t unless they figure this out soon.

At this point, what can we as fliers do? Nothing but wait for the result. No reason to bicker like this.

Quoting TheSultanOfWing (Reply 228):
Any info on what airframes are being checked physically?
Did Boeing send staff to NRT, ORD, DOH, SCL etc to check each and every plane, or is it just the batteries that are being dispatched and examined?

Boeing sent an investigator, same with Yuasa and the NTSB.
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 5:30 pm

Quoting Cubsrule (Reply 238):
Well, yes, it certainly can be. Fire is an acceptable risk in engines, for instance, because it's unavoidable and we have good ways of mitigating it. Engine fires happen on a fairly regular, if not routine, basis.


This isn't trivialising?

Please, let's not use extremism to counter statements.

I wouldn't say the two things are the same. You might, I wouldn't.

Quoting tdscanuck (Reply 178):
The issue with the current problem is that it might not comply with regulations that require the probability of a catastrophic event due to foreseeable *combinations* of failures must be extremely remote.

In other words- the probability might not be extremely remote. Therefore these fires are unacceptable- especially when there are other ways around it.

I'm not slating Boeing- but the problem requires a fix.
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 5:33 pm

Quoting spacecadet (Reply 202):
I'm not sure that some of you guys realize that your arguments boil down to putting economic concerns over human lives

Oh, we realize it. What I don't think many people realize is that that's how you *have* to design commercial systems. You can always spend more money to make airplanes (or any other system safer). But, at some point, it becomes so expensive that nobody flies.

Quoting spacecadet (Reply 202):
No plane should be flying if it's flying with an unknown level of safety.

All planes fly with an unknown level of safety. The regulators specify an upper bound on the risk and the OEM's have to show that they're below that bound with some reasonable confidence level, but none of them have a clue what their exact risk is.

Quoting spacecadet (Reply 202):
No amount of money is worth it.

Passengers aren't willing to pay more for safer airplanes. This is why the OEM's don't compete on safety. If you give me $10 billion I guarantee I can make the system safer enough to save at least one life...but nobody takes that deal.

The idea that any amount of money should be expended for arbitrarily small safety gains is, like "absolute safety", a myth.

Quoting seahawk (Reply 206):
The other problem is that those vent gases are considered possibly toxic. So they must not reach the cabin.

That's part of the general smoke/fume regulations. They test it by dumping smoke into the lower lobe compartments in flight and proving that it doesn't get onto the main deck.

Quoting s5daw (Reply 214):
Quoting faro (Reply 213):
nd smoke and fumes vented properly

Apparently at least the fumes part was problematic in the ANA incident...

There's no requirement (nor capability) for smoke containment to work on the ground with the doors open and the ECS off. On the ground, you evacuate.

Quoting liquidair (Reply 216):
you want to know what I can't understand keeps coming up? The fact that so many seem to be trivialising what is an extremely worrying series of events.

I'd like to see concrete examples of anyone trivializing the problem. Dialing the problem back from "everyone was going to die in minutes if they didn't land the plane!" is injecting reality, not trivializing.

Quoting liquidair (Reply 216):
You may insist that these fires were foreseen- and they were not dangerous-

They were foreseen, otherwise they wouldn't have wrapped the battery in a big steel box. Nobody that I'm aware of has claimed that they were not dangerous. Note that dangerous is not the same thing as loss of continued safe flight and landing, which is the safety requirement at issue.

Quoting liquidair (Reply 216):
I mean, are we really trying to debate over the fact that a flaming battery should be de rigeur?

No. Nobody is debating that.

Quoting liquidair (Reply 216):
That technological advancement with the 787 should inherently pose a threat to it's passengers?

All technology advancements post an inherent threat to the passengers because new technology comes with unknowns...that's what makes it new.

Quoting alfablue (Reply 230):
The FAA said it chose not to require special fire extinguishers and training because of the four redundant systems already in the Boeing system to prevent the battery from catching fire.

I'm not aware of any commercial airliner in existence where the crew are equipped and trained to fight a battery fire in an EE compartment. That's far more likely to result in loss of life than containing the fire and letting it burn out.

Quoting alfablue (Reply 230):
Below is the link to the special conditions (again) and you can see that point one is the containment, which is currently under investigation with unknown outcome. Point two however is violated (twice now)
....
(2) Design of the lithium ion batteries must preclude the occurrence of self-sustaining, uncontrolled increases in temperature or pressure.

Point 2 is a design constraint, not a manufacturing constraint. The battery *design* may well meet requirement 2. In-service failure of a battery does not violate point two if the failure is caused by a deviation between the design and the as-built (in which case it's a quality failure, not a design failure).

Quoting justloveplanes (Reply 231):
With regards to the above, I recall that the FDR didn't record an over voltage. Does it record current flow in and/or out? Combined current flow in (charging) and out (powering the APU or other load)?

Yes, it records current in/out.

Quoting justloveplanes (Reply 231):
There is also the possibility (and I don't know this) that the instrumentation might not adequately convey an overvoltage event, what resolution in time are these voltage readings stored?

FDR stores at several frequencies, I think the highest is 16 or 32 Hz. However, the maintenance systems watch at a much higher frequency and should catch and set a message for events that happen too quickly to make it on the FDR.

Quoting liquidair (Reply 232):
To my mind, whilst I understand the fact that the system have been designed to withstand failure, it's still just not acceptable to employ this technology if this rate of failure occurs.

I would say it's not acceptable to employ *this implementation* of the technology if this rate of failure occurs...which is exactly what the FAA said they're concerned about. Lithium batteries are used on the ISS, which is a *far* worse place to have any kind of fire, so it's clearly possible to design lithium technology to more stringent levels.

Quoting liquidair (Reply 236):
The technical explanations can go on until the cows come home- but the point that fire is unacceptable cannot be debated, in my view.

I don't think anyone is claiming fire is acceptable. What is being claimed is that fire is designed for, so that the mere occurrence of a fire does not, on its face, mean the airplane or passengers were in jeopardy.

Tom.
 
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Stitch
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 5:35 pm

Quoting PHX787 (Reply 240):
Yomiuri, USA Today, and Japan Today all saying that, like the JL frame, the NH plane at TAK did not suffer an over charge. Therefore it's something inherently wrong with the lithium ion batteries themselves.

At this point in my opinion, we can forget any 787 flights for the next month. Yuasa is now in the hot seat and all involved in the Li ion batteries at Yuasa are in deep sh*t unless they figure this out soon.

Well if they believe it's the battery, and not the 787's charging system, then I don't see why the 787 needs to remain grounded once "known good" batteries can be identified and procedures can be put into place to test them to ensure that they remain "known good".

While the 787 did have two battery incidents in about as many weeks, many seem to forget that the fleet had over 100,000 hours of revenue flying without a battery incident. JA804A - the NH plane - had flown for a full year without a battery incident. Three other NH planes had flown for over a year without a battery incident. And JL had two or three planes with nine months of service without a battery incident.

The above being said, I do not believe that once the fleet is returned to service with "known good" batteries and a testing regimen to ensure they remain "known good" that the case should be closed.

I believe Boeing should be ordered to design and test a more robust containment system to restore full confidence that if a "known good" battery suddenly goes "bad" and enters thermal runaway, there is evidentiary proof that the containment system will hold it for beyond 330 minutes (even if the batteries themselves lack the fuel to burn that long, ensuring no electrolyte leaks outside the container for such a period strikes me as prudent). It is believed that Airbus has chosen an "active discharge" process in which the liquid battery material is vented from the container directly into the atmosphere, which should prevent it from "bubbling over" and escaping the containment system.

And once that containment system is installed, Boeing should then be at least strongly encouraged to change the chemistry of the cathodes from the current lithium cobalt oxide to something like lithium nickel cobalt aluminum oxide, lithium nickel manganese cobalt or lithium iron phosphate due to their safer and more stable chemistry.
 
Cubsrule
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 5:37 pm

Quoting liquidair (Reply 241):
This isn't trivialising?

Nope, it's correcting a statement that is far too broad and thus wrong.

The fact that fire is not always unacceptable does not mean that battery fires are acceptable. But the fact that battery fires are fires does not, in itself, make them unacceptable.

Quoting tdscanuck (Reply 242):
What is being claimed is that fire is designed for, so that the mere occurrence of a fire does
not, on its face, mean the airplane or passengers were in jeopardy.

When I say that fire is acceptable, I intend that to mean exactly what you've said here. Different people are using somewhat different definitions of the word acceptable.
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liquidair
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 5:47 pm

Quoting Cubsrule (Reply 244):

A little pedantic, perhaps?

Quoting tdscanuck (Reply 242):

thank you- appreciated as always...

But..

Quoting tdscanuck (Reply 242):
All technology advancements post an inherent threat to the passengers because new technology comes with unknowns...that's what makes it new.

surely this is the whole point of testing? so that there are no risks once in service to the public... Boeing shouldn't really profit from using us as guinea pigs, no?

things have changed over time... corporations can't get away with that attitude anymore...
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Cubsrule
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 5:57 pm

Quoting liquidair (Reply 245):
surely this is the whole point of testing? so that there are no risks once in service to the public... Boeing shouldn't really profit from using us as guinea pigs, no?

You run in to the question of how much testing is necessary or desirable. The government has answered that question in different ways for different industries, but the common thread is that testing cannot - and should not be expected to - replicate all foreseeable in-service conditions nor does it replicate the total amount of time a product spends in service.
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Kaiarahi
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 5:58 pm

Quoting liquidair (Reply 245):
surely this is the whole point of testing? so that there are no risks once in service to the public... Boeing shouldn't really profit from using us as guinea pigs, no?

In that case, no aircraft would ever enter service. In order to know what the risks might be after 20 years of service and x,000 cycles, you'd have to test it for 20 years ....
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PITingres
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 6:16 pm

Quoting liquidair (Reply 236):
The technical explanations can go on until the cows come home- but the point that fire is unacceptable cannot be debated, in my view.

Sure, I'll debate it. It depends on what you mean by "unacceptable". An analogy would be the difference between a rotor burst and a fan blade-out in an engine. Rotor bursts are non-containable by any reasonable or even unreasonable means, and so you have to reduce their likelihood to very low levels. (And even then you have to make every attempt to mitigate the damage if it DOES happen. As I understand it, from a certification and design standpoint you aren't allowed to simply assume that a burst cannot happen, just that it will be very rare, with some agreed-upon very low probability.) Fan blade-outs are containable and so you design a containment system for that event. That *doesn't* mean that you don't try to minimize blade-out occurrences, because obviously you do. It doesn't mean that rotor bursts are serious and blade-outs aren't -- they are both serious. It simply means that you trade the design in different directions. If someone were to say "fan blade-outs are unacceptable" I would have to ask for clarification.

Going back to batteries, the phrase "fire is unacceptable" to me conveys the notion that you want to treat it on the same level as a rotor burst -- something that basically must not ever happen. That seems to be an unreasonable engineering trade and I disagree with it; better to assume some sufficiently low probability of battery fires and contain them if it happens. So far that strategy seems to have worked well. The problem as I understand it centers around that "sufficiently low" probability; with two fires in rapid succession, is there something going wrong that should not be?

As for whether that investigation, from a sample of two, is proper basis for a fleet grounding, I've no idea and I'm not qualified to speculate.

All of the above has been stated often enough, with what I would have thought was sufficient clarity, that many of the more recent "sky is falling" posts strike me as unreasonable. I don't doubt that some of it is deliberate trolling. Unfortunately that sort of brush paints a wide swath and labels the pure and impure of heart alike, I guess. If you are one of the former than I apologize. (and if one of the latter, then not so much.)
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RE: FAA Grounds 787 Part 4

Wed Jan 23, 2013 6:18 pm

Quoting Stitch (Reply 243):
Well if they believe it's the battery, and not the 787's charging system, then I don't see why the 787 needs to remain grounded once "known good" batteries can be identified and procedures can be put into place to test them to ensure that they remain "known good".

You just answered your own question. Developing and executing these procedures will take some time.
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