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B787 Grounding: Tech/ops Thread Part 2  
User currently offline777ER From New Zealand, joined Dec 2003, 12145 posts, RR: 17
Posted (1 year 6 months 1 week 4 days 13 hours ago) and read 14268 times:
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Link to the first thread: Tech/Ops Discussion Of The 787 Grounding (by CM Jan 22 2013 in Tech Ops)

114 replies: All unread, showing first 25:
 
User currently offlinekanban From United States of America, joined Jan 2008, 3547 posts, RR: 26
Reply 1, posted (1 year 6 months 1 week 4 days 4 hours ago) and read 14055 times:
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We've tried to keep this thread limited to facts and data limited to the 787 and it's specific battery. Wild speculations, 'similar to' scenarios, and blame game posts are not welcome.

User currently offlineRickNRoll From Afghanistan, joined Jan 2012, 824 posts, RR: 0
Reply 2, posted (1 year 6 months 1 week 3 days 22 hours ago) and read 13830 times:

Is there any truth to this claim.

ound this blog topic on the battery fire in Boston. Can anyone confirm the technical details?


The NTSB interim report into the Japan Airlines 787 battery fire in Boston in January says a second smaller lithium ion battery located above the large battery showed signs of failure before it was physically removed from the belly of the Dreamliner by an airport fire crew.

The implication is that had this main rear lithium-ion battery fire broken out while the JAL flight was making its flight from Narita to Boston there would have been a second stacked lithium ion fire in the same location directly under the rear passenger cabin just behind the trailing edge of the wing.

This smaller battery that was installed on a rack above the battery that burned was also supplied by Japanese manufacturer GS Yuasa, and was intended to provide emergency power for the jet’s flight controls for 10 minutes or more “when no other electrical power is available.”

The NTSB investigators found the exterior of this battery had been “lightly scorched” by the fire below and noted its case had openings at the corners.

The firefighters suppressed the fire before it could spread to that second battery.


http://blogs.crikey.com.au/planetalk...7-was-at-risk-of-2nd-battery-fire/

That is, that there is another, smaller lithium battery that was at risk of catching fire from the main battery catching fire.
Also, it appears that there was fire that had escaped containment. There was debate over weather this was due to the fire fighters, or if it had happened before the fire fighters arrived on the scene.


User currently offlineStitch From United States of America, joined Jul 2005, 30977 posts, RR: 86
Reply 3, posted (1 year 6 months 1 week 3 days 21 hours ago) and read 13804 times:
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There was truth that a second battery was "lightly scorched", but I am not sure that means it is true it would have subsequently caught fire itself.

I'm guessing this second battery is the one in the copper-colored box with the Honeywell label. Have to say that it looks completely undamaged in the NTSB picture of the APU battery location.


Quoting RickNRoll (Reply 2):
Also, it appears that there was fire that had escaped containment. There was debate over weather this was due to the fire fighters, or if it had happened before the fire fighters arrived on the scene.

That the firefighters reported flames were visible escaping the box when they arrived in the EE bay should have been clear enough evidence.

[Edited 2013-03-09 16:00:36]

User currently offlinehivue From United States of America, joined Feb 2013, 1077 posts, RR: 0
Reply 4, posted (1 year 6 months 1 week 3 days 21 hours ago) and read 13780 times:

Quoting RickNRoll (Reply 2):
a second smaller lithium ion battery located above the large battery showed signs of failure before it was physically removed from the belly of the Dreamliner by an airport fire crew.
Quoting Stitch (Reply 3):
I'm guessing this second battery is the one in the copper-colored box with the Honeywell label. Have to say that it looks completely undamaged in the NTSB picture of the APU battery location.

How could this "smaller lithium ion battery" appear in the NTSB photograph of the APU battery location in the airplane if the fire crew had removed it from the airplane?


User currently offlineStitch From United States of America, joined Jul 2005, 30977 posts, RR: 86
Reply 5, posted (1 year 6 months 1 week 3 days 21 hours ago) and read 13771 times:
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Quoting hivue (Reply 4):
How could this "smaller lithium ion battery" appear in the NTSB photograph of the APU battery location in the airplane if the fire crew had removed it from the airplane?

I don't believe they did. To my knowledge, they only removed the APU battery.


User currently offlinehivue From United States of America, joined Feb 2013, 1077 posts, RR: 0
Reply 6, posted (1 year 6 months 1 week 3 days 19 hours ago) and read 13712 times:

Oh, OK. I guess that blogger could use an editor. Will have to check the report to see if what he says is correct.

User currently offlineBoeingVista From Australia, joined Jan 2009, 1580 posts, RR: 3
Reply 7, posted (1 year 6 months 1 week 3 days 17 hours ago) and read 13657 times:

Quoting Stitch (Reply 3):
There was truth that a second battery was "lightly scorched", but I am not sure that means it is true it would have subsequently caught fire itself.

I dont think that people have looked at the below document that shows anothe 20 odd picyures of the fire scene.

Take a look at the pictures from page 10, the 10 minute avionics backup battery is clearly marked and does sit directly above the APU battery in a non fully sealed container, as it is on a rack directly above the burning APU battery it was receiving flame, heat and expelled electrolyte onto its bottom like it was on a hotplate, this cannot be good. More certification issues.

Also browse the pictures from page 10 down and read the fire-fighters report, the fire was not on its way out and imagine how much further damage could have been caused before it burnt itself out.

http://www.ntsb.gov/investigations/2...ket_documents/787_docket_doc19.pdf



BV
User currently offlineJoeCanuck From Canada, joined Dec 2005, 5455 posts, RR: 30
Reply 8, posted (1 year 6 months 1 week 3 days 14 hours ago) and read 13612 times:

Quoting BoeingVista (Reply 7):

All of the fire/smoke/spillover problems can be solved with containment. What happened didn't happen in the million or so hours of testing by Yuasa and Boeing. The cause of the fire itself is so elusive that the NTSB still doesn't have root cause for either fire...and that's the real problem with these batteries.

Without knowing why they went runaway, you can't fix it. I still hold with my initial reaction; shoehorn an interim battery using already certified chemistry, (NiCd), and get flying. It looks like there's lots of room in there for a longer battery pack to fit on the current batter rails, (if it needed to be longer). I'd be shocked if the 787 charging system couldn't be set for a NiCd pack.

So far, it's impossible to tell exactly what Boeing and the feds are doing, (I'd love to be a fly on the walls), but I'd bail on the current chemistry pronto, and to tell the truth, I'd bail on Li-ion chemistry altogether. No matter how benign the chemistry, (LiFePo4, for example), it's still LITHIUM and that stuff blows up planes, right...? (insert smiley here)



What the...?
User currently offline747classic From Netherlands, joined Aug 2009, 2141 posts, RR: 14
Reply 9, posted (1 year 6 months 1 week 3 days 10 hours ago) and read 13511 times:

I have some more (technical ) questions :

- How many Litium-ion batteries are in total installed in the 787 ? Three (3) are known to me up to now.

- Are all Litium-ion batteries affected by the Boeing solution for lifting of the 787 grounding (containment and extra ventilation) ?

- Is battery re-location also included in the Boeing proposed fix ?

- What is(are) exactly the function(s) of each battery ?

To start things up :

- AFAIK the Main and Avionics batteries are installed as the (last) electrical back-up for flight critical systems if all other electrical sources (engine, APU and RAT generators) have failed or after a total electrical grid failure.

- The APU battery is only used for APU starting and is needed for ETOPS certification, to deliver two extra serviceable APU generators, after an APU in flight start, if needed in a non-standard electrical procedure.
AFAIK the APU battery can't be used to augment the main battery in case of an electrical emergency.



Operating a twin over the ocean, you're always one engine failure from a total emergency.
User currently offlinehivue From United States of America, joined Feb 2013, 1077 posts, RR: 0
Reply 10, posted (1 year 6 months 1 week 3 days 4 hours ago) and read 13359 times:

Quoting JoeCanuck (Reply 8):
shoehorn an interim battery using already certified chemistry, (NiCd), and get flying. It looks like there's lots of room in there for a longer battery pack to fit on the current batter rails, (if it needed to be longer). I'd be shocked if the 787 charging system couldn't be set for a NiCd pack.

But there remains the major issue of whether any NiCad solution that could possibly be made to fit could also meet the 787's power requirements. In the Boeing video cited in other posts in other threads Mike Sinnett says Li-Ion was not chosen to save weight (i.e., for its size) but because of power requirements.



Quoting 747classic (Reply 9):
The APU battery is only used for APU starting

The APU controller is powered by the APU battery. If a the APU battery tanks the APU shuts down.

Quoting 747classic (Reply 9):
or after a total electrical grid failure

If there is no electrical grid at all available it's unlikely that batteries are going to be of any use.


User currently offlinercair1 From United States of America, joined Oct 2009, 1320 posts, RR: 52
Reply 11, posted (1 year 6 months 1 week 3 days 3 hours ago) and read 13342 times:
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Quoting 747classic (Reply 9):
How many Litium-ion batteries are in total installed in the 787 ? Three (3) are known to me up to now.

I don't know precisely - but multiple posts have mentioned that Li-Ion batteries are used throughout many aircraft both from Boeing and AirBus - and presumably others as well. Most of those batteries are quite small and back up individual items - like exit signs and the such.
The uniqueness of the 787 is the use of a large, high capacity Li-Ion for Main Ship and APU batteries. The AB350 was intended to do this as well, but AB has stated they will launch with NiCads and consider upgrade to Li-Ion later.

Quoting 747classic (Reply 9):
Are all Litium-ion batteries affected by the Boeing solution for lifting of the 787 grounding (containment and extra ventilation) ?

I don't think so. If that were the case, many other a/c would be impacted.

Quoting 747classic (Reply 9):
Is battery re-location also included in the Boeing proposed fix ?

I don't think so - but that is not authoritative. Has Boeing's proposal been released to the public?

Quoting 747classic (Reply 9):
What is(are) exactly the function(s) of each battery ?
Quoting 747classic (Reply 9):
To start things up :

I think you have it correct - with one minor comment.. I believe the main battery is intended to be an interim source while alternative sources come up. It is not considered one of the non-time limited extra sources. That is why the APU battery is there - to start the APU. The non-time limited sources include the main engine generators, the APU generators and the RAT.



rcair1
User currently offlinekanban From United States of America, joined Jan 2008, 3547 posts, RR: 26
Reply 12, posted (1 year 6 months 1 week 3 days 3 hours ago) and read 13336 times:
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Quoting rcair1 (Reply 11):
The AB350 was intended to do this as well, but AB has stated they will launch with NiCads and consider upgrade to Li-Ion later.

Read somewhere they will stay with Li-Ion on the first three test vehicles and change to NiCad on unit 4.. allowing them to meet first flight and test projections avoiding a 787 type delay. Evidently there needs to be software changes with the battery change.


User currently offlineStitch From United States of America, joined Jul 2005, 30977 posts, RR: 86
Reply 13, posted (1 year 6 months 1 week 3 days 3 hours ago) and read 13327 times:
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Quoting BoeingVista (Reply 7):
I dont think that people have looked at the below document that shows anothe 20 odd pictures of the fire scene.

Thank you for that. The bottom is indeed where the scorching happened.



Quoting 747classic (Reply 9):
- How many Litium-ion batteries are in total installed in the 787 ? Three (3) are known to me up to now.

Ship's Battery, APU Battery, Avionics Battery (not sure if there is just one in the aft EE bay or also one in the forward EE bay, as well). Li-Ion batteries also power emergency cabin lighting.



Quoting 747classic (Reply 9):
- Are all Litium-ion batteries affected by the Boeing solution for lifting of the 787 grounding (containment and extra ventilation) ?

No. The ones that power the emergency lighting are not considered a risk. The Avionics battery also seems to not be considered a risk.



Quoting 747classic (Reply 9):
- Is battery re-location also included in the Boeing proposed fix?

I am guessing no, but to my knowledge most of the particulars of Boeing's proposed fix have not been made public.

Quoting 747classic (Reply 9):
- What is(are) exactly the function(s) of each battery?

The Ship's Battery assists the APU battery during APU start. It also provides power to the Captain's instrument panel in the event of a loss of generator power (engine; APU; RAT).

The APU battery can start the APU on it's own, but normally is used in conjunction with the Ship's Battery for this function.

The Avionics battery is a new one to me, but it sounds like it's the terminal emergency power source for flight deck instruments.


User currently offlineRickNRoll From Afghanistan, joined Jan 2012, 824 posts, RR: 0
Reply 14, posted (1 year 6 months 1 week 3 days 2 hours ago) and read 13295 times:

Quoting hivue (Reply 10):
The APU controller is powered by the APU battery. If a the APU battery tanks the APU shuts down.

Is that correct? What that means is that you can't MEL the APU battery, if you need to have the APU available for ETOPS, doesn't it? The APU could be started with one engine still going, but it can't run at all without the APU battery being functional.


User currently offlineStitch From United States of America, joined Jul 2005, 30977 posts, RR: 86
Reply 15, posted (1 year 6 months 1 week 3 days 2 hours ago) and read 13284 times:
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Quoting RickNRoll (Reply 14):
What that means is that you can't MEL the APU battery, if you need to have the APU available for ETOPS, doesn't it?

You can dispatch with the APU battery (or an APU, for that matter) inoperative, but it limits you to ETOPS-180 (you must be within 180 minutes of landing at a suitable airport).

As it has been explained to me, this is the case for other Boeing Commercial Aircraft families, as well.

[Edited 2013-03-10 12:44:12]

User currently offlineJoeCanuck From Canada, joined Dec 2005, 5455 posts, RR: 30
Reply 16, posted (1 year 6 months 1 week 3 days 2 hours ago) and read 13280 times:

Quoting hivue (Reply 10):
But there remains the major issue of whether any NiCad solution that could possibly be made to fit could also meet the 787's power requirements. In the Boeing video cited in other posts in other threads Mike Sinnett says Li-Ion was not chosen to save weight (i.e., for its size) but because of power requirements.

Increasing capacity just means increasing the number of cells. Then, the limitations are size and weight.

The 787 battery is nominal 30v, 65Amp/hr, (with a normal operating range of between 20v and 30v) and the 777 battery is 28v, 50Amp/hr capacity. You basically have to add 30% more cells, (which means 30% larger size as well), to get the same capacity as the 787 batter...but I have no idea about the size and weight.

I'm having a heck of a time digging up the physical dimensions of the 777 battery pack, but individual cells don't really care how they're stacked so a pack could probably be built that would fit on the 787 battery rails, but probably stick out further, or be a bit taller.

Anyway, the gist of my position is that I can't wrap my head around why they don't stage the process, using an interim, alternate battery chemistry temporarily. Maybe certifying even a NiCd pack, (since it would have to be a unique pack, regardless of the chemistry being certified), would take as much time as getting the already certified pack fixed.

I don't claim to be an expert in batteries and there are a lot of smart boffins at Boeing working on this. I'm basically trying to understand what the heck is going through their minds, (because inquiring minds want to know), and I want to see that darned plane back in the air, (which I'm pretty sure is their goal as well).

At the same time, I like to solve problems so I don't mind speculating and offering solutions to the ether, which won't make a bit of difference in the long run, but keeps my neurons active.



What the...?
User currently offlinePITingres From United States of America, joined Dec 2007, 1144 posts, RR: 13
Reply 17, posted (1 year 6 months 1 week 3 days 2 hours ago) and read 13276 times:

Quoting hivue (Reply 10):
The APU controller is powered by the APU battery. If a the APU battery tanks the APU shuts down.

This apparently did happen on the ground, with no other power sources available (other than the Main battery). I too would like to know whether this is always the case if there are other power sources available: ground power, engine power, RAT, etc. I find it hard to believe that the APU can't be run at all in any circumstances without a functional APU battery.

It does seem a bit odd to have the APU controller requiring the APU battery when the APU itself is running, but no other power source is online. I have to wonder if the APU shutdown on JA829 was due to the way the airplane power was configured at that moment, or if it was a design oversight. I skimmed the NTSB report but I don't recall seeing any information on that point.



Fly, you fools! Fly!
User currently offlineStitch From United States of America, joined Jul 2005, 30977 posts, RR: 86
Reply 18, posted (1 year 6 months 1 week 3 days 2 hours ago) and read 13277 times:
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Quoting JoeCanuck (Reply 16):
The 787 battery is nominal 30v, 65Amp/hr, (with a normal operating range of between 20v and 30v) and the 777 battery is 28v, 50Amp/hr capacity.

Is the current provided at airplane power-up an issue? Per a Boeing presentation, the 787 battery can provide 150A while the 777 battery provides 16A.


Quoting JoeCanuck (Reply 16):
The 787 battery is nominal 30v, 65Amp/hr, (with a normal operating range of between 20v and 30v) and the 777 battery is 28v, 50Amp/hr capacity. You basically have to add 30% more cells, (which means 30% larger size as well), to get the same capacity as the 787 batter...but I have no idea about the size and weight.

Per the same Boeing presentation, the 787 battery uses 8 cells while the 777 battery uses 20 cells. That might impact the size and weight (the 777 battery weighs 48.5kg compared to 28.6kg for the 787).



Quoting PITingres (Reply 17):
I find it hard to believe that the APU can't be run at all in any circumstances without a functional APU battery.

This is evidently the case for all Boeing Commercial Airplane families.

[Edited 2013-03-10 12:51:55]

User currently offlinehivue From United States of America, joined Feb 2013, 1077 posts, RR: 0
Reply 19, posted (1 year 6 months 1 week 3 days ago) and read 13221 times:

Quoting RickNRoll (Reply 14):
Is that correct?
Quoting PITingres (Reply 17):
I have to wonder if the APU shutdown on JA829 was due to the way the airplane power was configured at that moment, or if it was a design oversight. I skimmed the NTSB report but I don't recall seeing any information on that point.

See footnote 6 of page 1 of the report:
"The APU battery provides power to start an APU during ground and flight operations. The APU controller (discussed in section 1.6.5) monitors the parameters that are needed to operate the APU. The APU controller is powered by the APU battery bus, which receives its power from the APU battery. If the APU battery fails, then the APU battery bus will no longer receive power, and the APU will shut down."

Quoting JoeCanuck (Reply 16):
Increasing capacity just means increasing the number of cells. Then, the limitations are size and weight.
Quoting Stitch (Reply 18):
Is the current provided at airplane power-up an issue? Per a Boeing presentation, the 787 battery can provide 150A while the 777 battery provides 16A.

I think that when they mention power requirements for the 787 they're talking about how many amps can be delivered, but I don't think it has to do with airplane power up but with emergency backup situations. I suspect that the electric brakes pull a lot of amps.


User currently offlineStitch From United States of America, joined Jul 2005, 30977 posts, RR: 86
Reply 20, posted (1 year 6 months 1 week 2 days 23 hours ago) and read 13148 times:
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Quoting hivue (Reply 19):
I think that when they mention power requirements for the 787 they're talking about how many amps can be delivered, but I don't think it has to do with airplane power up but with emergency backup situations.

The slide specifically noted this was current provided at airplane power-up.


User currently offlinehivue From United States of America, joined Feb 2013, 1077 posts, RR: 0
Reply 21, posted (1 year 6 months 1 week 2 days 20 hours ago) and read 13058 times:

Quoting Stitch (Reply 20):
The slide specifically noted this was current provided at airplane power-up.

Thanks. I should look at the video presentation again.

If the 787 actually needs 150A for routine processes it looks like the 777 can do on 16A then there may be no hope at all for a non-Li-Ion solution.


User currently offlinemjoelnir From Iceland, joined Feb 2013, 1449 posts, RR: 2
Reply 22, posted (1 year 6 months 1 week 2 days 19 hours ago) and read 13042 times:

Quoting Stitch (Reply 18):
Is the current provided at airplane power-up an issue? Per a Boeing presentation, the 787 battery can provide 150A while the 777 battery provides 16A.

You are comparing apples with bananas.

A is the current, A/h is the capacity.
The 787 has a battery of 65 A/h capacity and the 777 has a battery of 50 A/h capacity.

The 16 A draw of the 777 should be the draw (current) on the main battery.
Regarding the APU: if the draw for the APU start on the 787 would be 150 A and on the 777 16 A, than the APU on the 787 should be 10 times the size of the APU on the 777.
I think you should rethink your argument.


User currently offlineStitch From United States of America, joined Jul 2005, 30977 posts, RR: 86
Reply 23, posted (1 year 6 months 1 week 2 days 19 hours ago) and read 13018 times:
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Quoting mjoelnir (Reply 22):
You are comparing apples with bananas.

No, Boeing is, since it's their slide.

Quoting mjoelnir (Reply 22):
I think you should rethink your argument.

I think you should take it up with Boeing, since it's their slide.



[Edited 2013-03-10 19:57:14]

User currently offlineJoeCanuck From Canada, joined Dec 2005, 5455 posts, RR: 30
Reply 24, posted (1 year 6 months 1 week 2 days 18 hours ago) and read 13001 times:

NiCd's are famous for being able to handle high power draws. The capacity and current draw may have little to do with each other directly, except for duration of power delivery. Generally speaking, they are considered more reliable in high draw conditions than Li-ions...though I'm betting the 787 batteries aren't your standard power drill units.

It's only recently that power tools, (which tend to have a very high amperage draw), began switching to Li-ion batteries. It would take 44 of my Makita power tool batteries to equal the capacity and voltage of the 787 batteries.

I suspect that the 777 NiCd pack could handle a much higher draw than 16Amps. That's just what the 777 batteries are required to provide, not necessarily the maximum current they can supply 24v.
I'm guessing the 777 pack is made up of packs that resemble flashlight batteries, in series and parallel to provide the voltage and capacity.

IF the NiCd's could handle the higher draw, then the capacity and voltage would both have to be increased to match the 787 requirements and that would mean a battery of at least 150 lbs and probably 50% larger than the 777 batteries.

Even going with lead acid batteries might be possible. The gel battery in my motorcycle, (coincidentally a Yuasa), is 12v and 20 amp/hr. It's completely sealed, quite robust and designed for high current draws and random charging. 9 batteries like this with maybe 25 amp/hr capacity would give 36v and 75 Amp/hr total capacity in a package about 12"x12"x18"...but it would be one heavy sucker...probably in the 200 lb range.

I seriously doubt the charging system of the 787 couldn't be reprogrammed to handle either option. These batteries are not nearly as sensitive to charge and discharge variances as Li-ions. You could practically charge them with jumper cables from the baggage carts.

Bullet proof containment is probably the only way they can possibly get the Li-ion packs recertified and even then, they'll be a tough sell. I have a very difficult time believing they aren't working on a permanent solution using different chemistry, even if they stay within the Li-ion family. Cessna has chosen LiFePo4 for the CJ-4, which I think is a very good choice.

The end solution is the easy part....they'll have lots of time to come up with that. It's the interim solution which gets the planes back in the air that's the tough part.

If only they could come up with a root cause for the fires...then they could actually have something concrete to fix. It's the uncertainty and unpredictability that are the real buggers.



What the...?
25 kalvado : This makes me wonder - 777 battery should last for about 3 hours - capacity of 50 Ah/16 A draw.. 3 hours of what? Over the ocean flight with all engi
26 JoeCanuck : Just guessing but I suspect they did some intentional overkill on the battery. They had to use enough cells to get 24v out of 1.2v cells. They may ve
27 mjoelnir : I do not have to take it up with Boeing, it is your argument in this discussion. If you look at the advertisement slide of Boeing you presented, it i
28 Stitch : I didn't offer an argument, I asked a question: Rather than answer that question, you went with a tangential argument unrelated to my question.
29 mjoelnir : So about what is your question? The question could be can the Ni/cad provide the 150 A? The question could be is 150 A to much for the lithium/ion? C
30 CARST : But what could really be Boeings problem? You can not tell me that an 30-50% weight increase resulting in a battery weighing something around 70kg wo
31 JHwk : You could do a NiCd battery that would serve the purpose. It would be about 3x the weight and 2x the size based on total watt-hours for the system. Y
32 CALTECH : Posted this long ago in another thread which quickly became overrun with so-called 'experts' who knew everything such as the electrolyte makeup. This
33 JoeCanuck : The reason could be as simple as the certification process. Even using a certified chemistry, the charging system and application usage is different
34 mjoelnir : What exactly do people imagine happens when for example the Japanese or Chinese authorities will not accept a lithium ion solution even if the FAA doe
35 Post contains links Stitch : The FAA has given Boeing permission to move forward with their proposed fix.
36 Kaiarahi : FAA Press Release: The Federal Aviation Administration (FAA) today approved the Boeing Commercial Airplane Company’s certification plan for the rede
37 JoeCanuck : The cj-4 batteries are a different chemistry than the ones in the 787, but they are Li-ion. They chose to go with LiFePo4.
38 rcair1 : There are 3 things being done here - 2 are clear. One frustrates me because I'm unclear if precise precise usage of the term cell and battery is bein
39 bikerthai : This quote from Conner suggests no: "” Enhanced production and testing includes more stringent screening of battery cells prior to battery assembly
40 Kaiarahi : I have no authoritative source. However, NTSB/JTSB examination and testing has included the cells, connecting bars, BMU, BCU, and APU controller. The
41 JoeCanuck : It sounds to me like 'cell' refers to each of the 8 battery power units. It looks like they plan to insulate between the cells to prevent one runaway
42 Post contains images bellancacf : I'm interested in the mechanics of putting a vent to the outside in the battery compartment. (Into both compartments, I assume.) Is this commonly done
43 bikerthai : Yes, the lower lobe have these vents to dump air overboard. They are dumpling air all the time. Re-routing the air over the battery and dumping it to
44 cornutt : My understanding is that the main thing you have to do is seal or bond the cut edges so it doesn't de-laminiate there in the future. They do this sor
45 Post contains links dynamicsguy : I'm surprised this hasn't been mentioned yet. Boeing will be webcasting a technical briefing on the battery changes. Thursday 6pm US Pacific time, 9pm
46 bikerthai : This works fine for race care because the life cycle of the frame is limited and it does not have the delta pressure as seen by an airplane fuselage.
47 Kaiarahi : Tom and/or CM explained the process in one of the civav threads. Unfortunately, they've both left. I wonder if they'd even need new vent holes, or if
48 Humanitarian : Installing the vent should be routine for an experienced sheet-metal mechanic trained in CFRP. Speaking generally: drill a hole, install a doubler wit
49 Post contains images hivue : And from Tokyo. I guess that makes PR/marketing sense as JAL and ANA are the most affected airlines and Yuasa is the battery cell manufacturer.
50 bikerthai : If I was designing . . . it would depend on if there is an existing vent near by. Trying to route a tube (titanium?) to and existing hole may be more
51 Post contains images KELPkid : I'm wondering, too, if the LiIon battery pack for emergency flight control power is being moved from its current location directly on top of the APU b
52 hivue : Not if the new containment strategy works like it's supposed to.
53 Aircellist : I hope we'll see them soon, once this trouble with the 787 is over...
54 Post contains links taru : Webcast link: http://787updates.newairplane.com/Certification/Webcast And the slide show to go with the webcast is already available: http://787update
55 JHwk : Interesting solutions. Curious on two things though: -How do they deal with heat rejection from the battery? Cessna has finned heat sinks on their box
56 hivue : I'm curious about that as well. Mike Sinnett said that "fire" is impossible in the enhanced enclosure, but I wonder if highly energetic oxidation in
57 Post contains images Stitch : It is a misconception that a Li-Ion cell burns because it produces it's own oxygen (a misconception I myself shared, so I am throwing no stones here.
58 Post contains links and images Revelation : You win the prize - this is exactly what we are being told today. In http://seattletimes.com/html/busines...0561865_787batterybriefingxml.html we rea
59 7BOEING7 : Next time I run into him at the Teryaki place down the hill I'll mention that to him. From the sounds of the description on the news conference there
60 Post contains images bikerthai : This is what I also understand. Which means when the cell heats up, the delta pressure would have to be high enough to break the disc: Higher than th
61 hivue : Isn't that around 10 or 11 psi?
62 Post contains images Revelation : I appreciate that, but I imagine he has more important things on his mind! The reports in the press aren't mentioning such a disc, so I'll have to wa
63 bikerthai : Looks like 11 psi at 6000 ft altitude and 2.7 at 40,000 ft altitude. Delta P would then be about 8.3 psi. From a reliability stand point, the rupture
64 hivue : I don't know what kind of pressures could develop in a worse case battery failure in the new sealed up containment, but I suspect that the pressure r
65 twiga : I don't think the worst case comes into play since the disk in the vent tube will rupture and release pressure long before 8 cells fail. I presume th
66 prebennorholm : We haven't heard much about the valves involved in this new pressure box. We can only guess. I have a feeling that it may be rather complicated. It is
67 PITingres : I could probably convince myself that no valving is needed at all. Just leave the vent tube open, perhaps with some sort of positive closure that is n
68 francoflier : That is my main question as well. On the battery side, the focus seemed to be on better cooling of the battery, or at least the individual cells. On
69 Post contains images hivue : What valves are those? There is a disc that ruptures in the event of a sufficient build-up of pressure in the containment vessel following battery fa
70 Post contains links twiga : I think a lot of your questions can be answered if you go to http://www.boeingblogs.com/randy. There is a good picture of the new battery arrangment.
71 bikerthai : You don't want the battery enclosed space to be continuously open to the out side air as the constant change in pressure will result in unwanted mois
72 Post contains images kanban : Boeing tooling is designing a removal tool that consists of two plates, a mass of gears, 20 sockets, and is driven by a standard Li-ion home depot por
73 Post contains images KELPkid : The FAA might take issue with that. What if a maintenance crew accidentally left behind an unauthorized 18 or 20 v DeWalt LiIon battery pack in the E
74 Post contains links twiga : I just found the following article http://blogs.wsj.com/japanrealtime/2013/.../thermal-runaway-on-787 and I must say that I am now confused. I also o
75 kanban : As I read the available information, there is very little O2 available in the electrolyte and battery materials. This was confusing since there are o
76 rwessel : One additional small hole in the fuselage won't make any difference - the (vastly larger) outflow valves will just close down a tiny bit to maintain
77 justloveplanes : yes, and there doesn't seem to be redundant vent lines. A manifold output with multiple rupture discs is an trivial cost increase and I think warrant
78 hivue : My understanding is that the system is "inerted" in the sense that it has been engieneered to make it so that there never is sufficient oxygen presen
79 7BOEING7 : If you're talking about the Boeing design, I believe its "basically" self-inerting--the amount of oxygen available within the containment vessel is m
80 mham001 : For true capacities, you need to note the voltages as well.
81 twiga : You might be right but can't really tell from the photo, but then again there might be a vent tube behind that we can't see. The problem with vent ho
82 bikerthai : Looking at the design, the containment will probably not rupture. I see the weak link at the bulk-head connector for wire pass thru. If anything blow
83 twiga : This is what I originally thought as well. But Sinnett made this big deal about overcharging and 4 levels of protection to stop thermal runaway from
84 twiga : Ah so finally we get something for free - the mechanics would like it since it would be removed for them when they do the change out. So it sounds li
85 bikerthai : This was where Sinnet and the reporters were having a "back and forth". From what I understood, Sinnet was defining a run-away event from the "big ba
86 ContnlEliteCMH : This description of his words does him a disservice. He said the following: (1) He was concerned about events at an airplane level. At that level, th
87 7BOEING7 : His presentation to the flight crews after the ZA002 incident was just as impressive--excellent, knowledgeable speaker--an engineer first.
88 twiga : I was simply trying to paraphrase what I said in my post #74 and obviously did a bad job. This small quote here puts things out of context without lo
89 Post contains images bikerthai : Hum . . . Plan B may just be the same phylosophy except now make the containment box part of the battery shell itself (sealed battery with stainless
90 bellancacf : Sounds as if that would make replacing the battery a much pricier procedure. Myself, I was wondering if they were going to make the box big enough to
91 nomadd22 : I think that was me. Iron phosphate type Lithium batteries are lower voltage and would require 9 cells instead of 8. They have a little less capacity
92 kanban : There are too many unknowns in this.. yes there is a battery with a different chemistry that would require an extra cell, but if we now have time to
93 twiga : Could be if they are looking at shedding 100 lbs or more, in which case they would likely use titanium to keep the weight down and make it easier to
94 bellancacf : Thanks to all for very thoughtful answers. Patient, too! Yes, I hope they have kept all options open. There could be a number of reasons to move to a
95 prebennorholm : To fit in a 28VDC system one more cell will be needed. But that's not the only issue. Li-Fe has a energy density which is roughly 33% lower than Li-I
96 nomadd22 : Boeing doesn't just go to Radio Shack and buy cells. They'd be made to spec, in whatever shape they need to be. Cylindrical is just the cheapest way
97 blrsea : How are the batteries cooled in the airtight environment of the sealed box? The batteries will generate some amount of heat naturally as they go throu
98 Kaiarahi : See posts 67-81.
99 twiga : You are responding as if we specifically said they will be going to Li-Fe batteries. I said they would be "keeping all options open" and I also said
100 Post contains links 7BOEING7 : Here we go, flight plan filed for LOT ZA272. http://flightaware.com/live/flight/BOE272
101 HAWK21M : Anyone aware of the storage schedule followed on the type.....
102 cornutt : Question: Is the ship's battery required for deployment of the RAT? Or is that entirely mechanical?
103 joecanuck : I deal with electric bikes and for now, all i use are LiFePo4 batteries and the individual cells are rectangular. There is little preventing having s
104 bikerthai : As far as I'm aware and what everyone is telling me, the RAT is gravity deployed when there is a lack of electrical power. bt
105 7BOEING7 : Rat deploys with: Loss of both engines Low pressure on all three hydraulic systems Loss of all power to the Capt's/FO's flight instruments So what we
106 twiga : Thanks for your answer. I recall reading back in some threads that their deployment was'nt always that reliable - I was particularly thinking about c
107 Post contains links rcair1 : This might be of interest to people who have been following the B787 battery issues. http://www.ntsb.gov/news/events/2013/batteryforum/index.html Foru
108 Post contains links 7BOEING7 : Must not be grounded anymore Something's happening: http://flightaware.com/live/flight/BOE380 (GUN LN 34 B-1) http://flightaware.com/live/flight/BOE51
109 Stitch : Per Matt Cawby, the ANA flight is a functional systems check of the new battery containment system. That being said, that Boeing is starting "B2" flig
110 Post contains images airtechy : How do you vent the new battery to the outside via a "hole" without impacting the pressurization of the airplane? Maybe the battery compartment is sea
111 7BOEING7 : There are already two big holes in the airplane (outflow valves) which modulate throughout the flight to maintain the proper pressurization -- they w
112 bikerthai : During regular operation, the batter compartment is kept under cabin pressure by a disc which will rupture under a thermal runaway condition. During
113 Post contains images KELPkid : Isn't the pressurization system designed with enough margin to keep the cabin pressurized even if a single cabin window blows out?
114 7BOEING7 : No, it's good but not that good. Even harder with the 787 larger windows. As opposed to what you see/hear in movies/tv a bullet hole wouldn't be a bi
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