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SheikhDjibouti
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 2:42 am

Stitch wrote:
3) To that end, the 787 batteries need to be able to be quickly recharged to a level necessary to support those critical systems if discharged to support other functions. Example would be using battery power to perform an engine start then having to perform an RTO soon after.

This keeps getting thrown up as a reason, but it is a red herring. Firstly, all designs of Li-ion cells that I have met feature fast-charging. How fast is open to discussion.

Currently, one of my cars has a battery issue, and after a difficult cold start, it might not have enough reserve to repeat those starting duties if I go to the shops and turn the engine off. The answer, and it's not exactly a new idea, is to run the engine for a while longer than normal, purely in order to recharge the battery. So I reach the shop 10 minutes late. Big deal!

The answer for the B787 is the same. IF ground power is unavailable, and IF the APU sucks up an excessive amount of battery charge getting started, then..... you simply delay take-off for 10 minutes to allow the APU (and/or the main engines) a chance to recharge the battery unit(s).
The 787 "has very high power generation capability, making a total of 1.5 megawatts in flight from 6 Variable Frequency Starter-Generators (VFSG), with two on each engine, and two in the aft Auxiliary Power Unit (APU)."
The limiting factor is almost certainly overheating of the Li-Ion cells if you try to charge them too quickly. But 10 minutes extra on the ground will most likely make a big difference, and yet it shouldn't be necessary in 99.9% of cases. Or is the 787 still having serious issues with GPUs?
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Stitch
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 3:04 am

iamlucky13 wrote:
Something to emphasize here is I'm pretty much certain the 787 batteries are not composed of 8 cells, each 9 Ah in capacity, at 3.7V, for a total capacity of 72Ah at 3.7V. Rather, they should be each 72Ah in capacity, for a total capacity of 72Ah at 29.6V. Likewise for the A350, they're not 3Ah cells totaling 45Ah at 3.6V (or 56Ah as I suggest in my post), but 45Ah cells (or again, 28Ah cells arranged 7s2p) totaling 45Ah at 25.2V.


Per the A350 Blog, each of the Saft batteries consists of 14 cells storing a combined 45Ah of energy and running at 3.6V. Yuasa batteries onboard the 787 consists of 8 cells storing a combined 72Ah of energy and running at 3.7V. Per Boeing documents, the 787 battery is 32V total. Per Saft's documents, the A350 battery is 28V total. The 787 uses two batteries (one main and one APU) and the A350 uses four (three system and one APU).

I am not sure Saft has ever said what electrolyte formulation they use and there has been speculation it might be lithium nickel manganese oxide (the voltage apparently rules out lithium iron phosphate) instead of the lithium cobalt oxide used in the 787's.
Last edited by Stitch on Wed Dec 06, 2017 3:13 am, edited 1 time in total.
 
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Classa64
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 3:12 am

What about a small fuel cell instead of batteries... Just trying to think outside the box. :duck:
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 3:32 am

SheikhDjibouti wrote:
Stitch wrote:
3) To that end, the 787 batteries need to be able to be quickly recharged to a level necessary to support those critical systems if discharged to support other functions. Example would be using battery power to perform an engine start then having to perform an RTO soon after.

This keeps getting thrown up as a reason, but it is a red herring. Firstly, all designs of Li-ion cells that I have met feature fast-charging. How fast is open to discussion.

Currently, one of my cars has a battery issue, and after a difficult cold start, it might not have enough reserve to repeat those starting duties if I go to the shops and turn the engine off. The answer, and it's not exactly a new idea, is to run the engine for a while longer than normal, purely in order to recharge the battery. So I reach the shop 10 minutes late. Big deal!

The answer for the B787 is the same. IF ground power is unavailable, and IF the APU sucks up an excessive amount of battery charge getting started, then..... you simply delay take-off for 10 minutes to allow the APU (and/or the main engines) a chance to recharge the battery unit(s).
The 787 "has very high power generation capability, making a total of 1.5 megawatts in flight from 6 Variable Frequency Starter-Generators (VFSG), with two on each engine, and two in the aft Auxiliary Power Unit (APU)."
The limiting factor is almost certainly overheating of the Li-Ion cells if you try to charge them too quickly. But 10 minutes extra on the ground will most likely make a big difference, and yet it shouldn't be necessary in 99.9% of cases. Or is the 787 still having serious issues with GPUs?


I can't clarify how that factored into Boeing's decision versus Airbus', but I can provide some other related facts that may or may not be helpful

The 787 batteries charge at 46 Amps, which is 70% of their rated capacity per hour (0.7C).

Generally lower charge rates are easier on batteries, but the benefits of slowing the charge rate tend to decrease below 1C and become close to negligible below 0.5C. Some chemistries are more tolerant than others of high charge rates, but the rate Boeing uses is fairly typical. With many lithium ion battery variants, heat isn't a concern until you get up around 2C or so (130A for the 787 battery), but that would be a very large charger, and charging at 2C significantly reduces the useful life of the battery.

An APU start should peak around 650A and last less than 45s (those are the battery test criteria. I'm not sure what the actual load profile is). That would be 8 Ah of drain, so the battery should retain most of a charge after starting the APU.

10 minutes can be a big deal for airlines (consider also the concerns about cool down times for GTF-equipped A320 NEO's), but I don't have information on whether there is a state of charge criteria at the time of takeoff that affected Boeing's battery choice.

You generally wouldn't use a battery in a commercial application like this until it can barely perform its job before replacing it like we often do for personal use, like your car example. Typically, batteries in this kind of application are replaced when their capacity or current output drops to a specified level that is often 70-80% of their rating.
 
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 4:08 am

Stitch wrote:
iamlucky13 wrote:
Something to emphasize here is I'm pretty much certain the 787 batteries are not composed of 8 cells, each 9 Ah in capacity, at 3.7V, for a total capacity of 72Ah at 3.7V. Rather, they should be each 72Ah in capacity, for a total capacity of 72Ah at 29.6V. Likewise for the A350, they're not 3Ah cells totaling 45Ah at 3.6V (or 56Ah as I suggest in my post), but 45Ah cells (or again, 28Ah cells arranged 7s2p) totaling 45Ah at 25.2V.


Per the A350 Blog, each of the Saft batteries consists of 14 cells storing a combined 45Ah of energy and running at 3.6V. Yuasa batteries onboard the 787 consists of 8 cells storing a combined 72Ah of energy and running at 3.7V. Per Boeing documents, the 787 battery is 32V total. Per Saft's documents, the A350 battery is 28V total. The 787 uses two batteries (one main and one APU) and the A350 uses four (three system and one APU).

I am not sure Saft has ever said what electrolyte formulation they use and there has been speculation it might be lithium nickel manganese oxide (the voltage apparently rules out lithium iron phosphate) instead of the lithium cobalt oxide used in the 787's.


I hope I'm not just being tiresome in reiterating my stance, but with the prior mention of 3Ah and 9Ah cells, it sounds to me like those figures are not being understood correctly.

The 32V and 28V mentioned are at full charge of about 4V per cell for both batteries. The 3.6V and 3.7V figures are the numbers to use, in combination with the Ah numbers, for energy capacity.

8 x 72Ah cells at 3.7V nominal, hooked up in series, create a 72Ah, 29.6V nominal (32 V when fully charged) battery. This is a normal way of discussing battery ratings.

It is unusual to talk about a 72Ah battery made up of 9Ah cells connected in series because in series it is voltage that adds, not current. On the other hand, it would be normal to talk about a battery made up of 9Ah cells connected in parallel as being a 72Ah battery, but that battery would still be a 3.7V nominal battery.

So my reading of the specs, which also is in the expected range for lithium-ion energy density compared to the mentioned battery weights:

787
8 cells x 72ah x 3.7V = 2131 Wh/battery
2 batteries plus the flight control electronics battery yields 4560 Wh total onboard battery capacity.

A350
14 cells x 45ah x 3.6V = 2268wh/battery
4 batteries equals 9072 Wh total onboard battery capacity, or twice what the 787 has.

However, I clarified in a previous post that the A350 battery actually sounds like it has the 14 cells wired up in two parallel strings, which means the cells are actually 22.5ah each*. Each string then would be 28V fully charged and 22.5 Ah, so the two strings together total 45Ah.

That would mean the A350 and 787 actually have roughly equal total battery capacity.

As a minor note to avoid confusion about terms, the chemistries you mention are the cathode formulation, not the electrolyte. Lithium nickel manganese oxide does indeed sound like a likely candidate for the A350 cathode.

* Ignore my prior reference to 28 Ah. It's a small difference I can explain further if anybody is really curious.
 
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 4:47 am

iamlucky13 wrote:
I hope I'm not just being tiresome in reiterating my stance, but with the prior mention of 3Ah and 9Ah cells, it sounds to me like those figures are not being understood correctly.


Probably not since I am not an electrical engineer. I just divided the Ah by the number of cells. If that's wrong, fine.


iamlucky13 wrote:
That would mean the A350 and 787 actually have roughly equal total battery capacity.


Okay. I don't know what the electrical needs for the A350 are, but maybe it's systems need as much juice as the 787's even though they are not electrically-driven.


iamlucky13 wrote:
As a minor note to avoid confusion about terms, the chemistries you mention are the cathode formulation, not the electrolyte. Lithium nickel manganese oxide does indeed sound like a likely candidate for the A350 cathode.


Yeah I know it's the positive (cathode) electrode formulation. All these terms being thrown around starts to muddle together. I'll try to be more specific going forward.
 
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 5:37 am

Polot wrote:
KLDC10 wrote:
scbriml wrote:

As long as the containment system is doing its job, why would a battery failure need to be reportable?

It would be an entirely different situation if the containment failed.


Simply, because you don't need a containment system if something is working as it ought to.

With that school of thought you don’t need any redundancies in aircraft design. Why have backups/multiple systems doing/computing the same thing? You don’t need them if something is working as it ought to. Why even have all those emergency exits? You don’t need them if everything. Is working as they ought to.

There is not a container around everything. Some components need one, some not. The battery should not need one. IIRC, the images of the battery showed that the cells did not even have some cell balancing capabilities. That's dilettantish. My hobby grade lipo charger for 50€ has it....
 
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 5:57 am

The idea that since the containment worked this is not concerning is truly mind boggling!
 
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 7:03 am

QueenoftheSkies wrote:
The idea that since the containment worked this is not concerning is truly mind boggling!

There are literally thousands of inherent dangers on an airplane in flight. But they are contained or mitigated by redundancy or a safety system. For example the oxygen mask stored above your head in a way works as a containment system. It will keep you alive until you can get on the ground. The fan case on an engine is a containment system. It keeps you from being ripped to shreds if a blade fails.

The point is that there are thousands of things that could kill you in flight, since flying is inherently dangerous, but we accept the risks because there are acceptable safety systems in place. The battery box is no different than any other containment system on an airplane. I don’t see why you think there should be concern especially since the system worked.
 
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 8:31 am

QueenoftheSkies wrote:
The idea that since the containment worked this is not concerning is truly mind boggling!


What do you actually find mind boggling?

That the containment system worked as designed?

That 787 batteries continue to fail?

That some here don't consider a working containment system to be a flight safety risk?

That the certifying authorities don't need to be notified of battery failures?
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 9:01 am

Stitch wrote:
iamlucky13 wrote:
Something to emphasize here is I'm pretty much certain the 787 batteries are not composed of 8 cells, each 9 Ah in capacity, at 3.7V, for a total capacity of 72Ah at 3.7V. Rather, they should be each 72Ah in capacity, for a total capacity of 72Ah at 29.6V. Likewise for the A350, they're not 3Ah cells totaling 45Ah at 3.6V (or 56Ah as I suggest in my post), but 45Ah cells (or again, 28Ah cells arranged 7s2p) totaling 45Ah at 25.2V.


Per the A350 Blog, each of the Saft batteries consists of 14 cells storing a combined 45Ah of energy and running at 3.6V. Yuasa batteries onboard the 787 consists of 8 cells storing a combined 72Ah of energy and running at 3.7V. Per Boeing documents, the 787 battery is 32V total. Per Saft's documents, the A350 battery is 28V total. The 787 uses two batteries (one main and one APU) and the A350 uses four (three system and one APU).

I am not sure Saft has ever said what electrolyte formulation they use and there has been speculation it might be lithium nickel manganese oxide (the voltage apparently rules out lithium iron phosphate) instead of the lithium cobalt oxide used in the 787's.


The 787 battery is 8s ( i.e. 8 cells in a row , ~32V nominal )
I've never understood the redundancy arrangement ( and if there is any).

The A350 battery is 7s2p ( 7 in a row, two strings in parallel. ~28V nominal, regular aircraft bus )
IMU the 4 A350 bats are arranged in a 2 x 2 symmetric redundant arrangement.
The cells seem to be closely related to the SAFT VLM series. ( cylindrical cells )

couple years ago I asked for a product plus engineering offer from Saft for a medium size marine propulsion application.
( to replace a set of Zebrabatteries ( liquid sulfur electrolyte, hot! ) a bit on the pricy side.
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 9:05 am

scbriml wrote:
QueenoftheSkies wrote:
The idea that since the containment worked this is not concerning is truly mind boggling!

That the certifying authorities don't need to be notified of battery failures?


This
and the apparent corollary that nobody or the NTSB has any further interest in why they fail.
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 9:10 am

iamlucky13 wrote:
The A350 doesn't appear to have the 787's massive containment box, but it sounds like it is fully enclosed and vented like the 787's.


Google gives us the following picture:

Image

Image
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WIederling
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 9:33 am

Mercedes Benz hybrid lithium car battery, couple years older than 787 or A350 bats:
Image
quite a bit of management and environmental control wrapped around the cells.
one reason I was a bit astonished when the 787 imagery was shown.
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 10:26 am

WIederling wrote:
This
and the apparent corollary that nobody or the NTSB has any further interest in why they fail.


If they are failing safely, the containment is doing its designed job and there is no threat to flight safety, why should they have further interest in why they fail?

It seems to me it's no longer a safety issue, but one of reliability. In that case Boeing and Yuasa should be far more interested than the safety boards or certifying authorities.

It is absolutely a different kettle of fish if containment fails. :yes:
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SheikhDjibouti
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 10:33 am

SheikhDjibouti wrote:
Stitch wrote:
3) To that end, the 787 batteries need to be able to be quickly recharged to a level necessary to support those critical systems if discharged to support other functions. Example would be using battery power to perform an engine start then having to perform an RTO soon after.

The answer for the B787 is ..... IF ground power is unavailable, and IF the APU sucks up an excessive amount of battery charge getting started, then..... you simply delay take-off for 10 minutes to allow the APU (and/or the main engines) a chance to recharge the battery unit(s).

All designs of Li-ion cells that I have met seem to allow fast-charging; the limiting factor is overheating of the Li-Ion cells if you try to charge them too quickly.


iamlucky13 wrote:
The 787 batteries charge at 46 Amps, which is 70% of their rated capacity per hour (0.7C).
Now you are talking my kind of numbers. :D

An APU start should peak around 650A and last less than 45s (those are the battery test criteria. I'm not sure what the actual load profile is). That would be 8 Ah of drain, so the battery should retain most of a charge after starting the APU
I've got 450A for 45s, which could indeed be the load profile, or a misprint, but let's not argue. That 10 minutes to re-charge is looking pretty rosy. And as you say; the APU start hasn't killed the battery in the first place. Total red herring.

10 minutes can be a big deal for airlines
Ok, if you are at a location where you know ground power will be unavailable for some reason; the pilots must arrive and start up 10 minutes early, or 20, in order to avoid take-off delays. And maybe re-charge the cells from APU alone to avoid upsetting the engine parameters. And maybe continue to run the APU through the take-off & climb out if there is a risk that extra power is needed for an RTO or an immediate return to the field. Lots of alternative solutions here, but as I said before, I would hope these are one-in-a-thousand events anyway. Ground power is the preferred answer.

The rest of what you came up with was all good stuff too; big thanks for that. :wave:
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Revelation
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 12:20 pm

B737900ER wrote:
QueenoftheSkies wrote:
The idea that since the containment worked this is not concerning is truly mind boggling!

There are literally thousands of inherent dangers on an airplane in flight. But they are contained or mitigated by redundancy or a safety system. For example the oxygen mask stored above your head in a way works as a containment system. It will keep you alive until you can get on the ground. The fan case on an engine is a containment system. It keeps you from being ripped to shreds if a blade fails.

The point is that there are thousands of things that could kill you in flight, since flying is inherently dangerous, but we accept the risks because there are acceptable safety systems in place. The battery box is no different than any other containment system on an airplane. I don’t see why you think there should be concern especially since the system worked.


Indeed. If you want to have some concerns, consider that the fan case on the engine is designed to contain a blade failure but not a disc failure. Disc failure is supposed to be ruled out totally via inspections, but has happened a handful of times, including the infamous QF32 ( ref: https://en.wikipedia.org/wiki/Turbine_e ... _incidents ). A failing disc has much more mass and thus much more momentum than a failing blade, and it would be uneconomic to fly an engine that could contain a disc failure, so we don't.

Basically, if an inspector misses a flaw your day could end poorly, or even your life.

So, here we spend time on a containment system that works, whereas ignore a case where one doesn't, even after witnessing such failures.

Image
Last edited by Revelation on Wed Dec 06, 2017 12:28 pm, edited 1 time in total.
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 12:25 pm

scbriml wrote:
That 787 batteries continue to fail?



My only concern would be whether the batteries are failing earlier and with more frequency than was predicted. This I am sure will be investigated and if action needs to be taken I am sure the relevant safety authorities will publish the needed action.
 
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 12:53 pm

WIederling wrote:
scbriml wrote:
QueenoftheSkies wrote:
The idea that since the containment worked this is not concerning is truly mind boggling!

That the certifying authorities don't need to be notified of battery failures?


This
and the apparent corollary that nobody or the NTSB has any further interest in why they fail.


Because NTSB is waiting for the promised permanent fix by the vendor. What are JCAB and JTSB doing?

One data point NTSB should investigate is how many 787 batteries/cells were swapped as part of "routine" maintenance by Japanese carriers.
 
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SheikhDjibouti
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 1:21 pm

enzo011 wrote:
My only concern would be whether the batteries are failing earlier and with more frequency than was predicted. This I am sure will be investigated and if action needs to be taken I am sure the relevant safety authorities will publish the needed action.

aviationtoday.com; 2013 wrote:
The failure analysis of the battery system on the 787 foresaw a battery thermal failure event as being something so rare it could be expressed in terms of once in 10 million flight hours, but actually one failure occurred within 196 flight hours, another within 2151 hours, a very troubling discrepancy of projected reliability. Many public statements claimed that the faults occurred after 52,000 flight hours, but this is not correct. That higher total was taken from the combined totals of all 50 aircraft in service and test flights.
Are they right, or are they wrong? (reminder; this was 2013)
Even if we take the figure of 52,000 hours for the combined fleet, it's hardly flattering.
How are the numbers looking now we are in 2017?

dtw2hyd wrote:
One data point NTSB should investigate is how many 787 batteries/cells were swapped as part of "routine" maintenance by Japanese carriers

I should imagine the NTSB would be at least mildly interested in these numbers.
But I would imagine the airlines themselves would be even more interested, not from a strict safety angle, but from an economic viewpoint.
Their highly reliable, low maintenance 787 Dreamliner is more like an unreliable, high maintenance 787 Nightmare.
(ok, maybe I'm exaggerating there, but it's only poetic license) :D
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kalvado
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 1:46 pm

B737900ER wrote:
QueenoftheSkies wrote:
The idea that since the containment worked this is not concerning is truly mind boggling!

There are literally thousands of inherent dangers on an airplane in flight. But they are contained or mitigated by redundancy or a safety system. For example the oxygen mask stored above your head in a way works as a containment system. It will keep you alive until you can get on the ground. The fan case on an engine is a containment system. It keeps you from being ripped to shreds if a blade fails.

The point is that there are thousands of things that could kill you in flight, since flying is inherently dangerous, but we accept the risks because there are acceptable safety systems in place. The battery box is no different than any other containment system on an airplane. I don’t see why you think there should be concern especially since the system worked.

Blade out on engine - and that is scenario for engine shroud - is a reportable event, as far as I understand - especially on ETOPS flight
Not sure about pressurization loss, but I suspect it is...
 
WIederling
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 1:58 pm

dtw2hyd wrote:
WIederling wrote:
scbriml wrote:
That the certifying authorities don't need to be notified of battery failures?


This
and the apparent corollary that nobody or the NTSB has any further interest in why they fail.


Because NTSB is waiting for the promised permanent fix by the vendor. What are JCAB and JTSB doing?

One data point NTSB should investigate is how many 787 batteries/cells were swapped as part of "routine" maintenance by Japanese carriers.


Initially the change out rate was rather high.
Mostly due to depleted batteries from "standing around".
Lots of actions that dialed up battery demand that was not realized by involved personel.
( fuel indication, cabin emergency lighting, doors ,,....)
a "run below minima battery had to be taken out for off site servicing ( or repair ).

Another early known issue was limited lifetime from regular use. going by Jon Ostrower this was known even before FF.
A change in battery chemistry was looked at ( but I could never verify that this was ever effected.)

" What are JCAB and JTSB doing? "
Moot. NTSB was actively involved and primary investigator in the path to the certification authority ( FAA ).
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 2:01 pm

SheikhDjibouti wrote:
I should imagine the NTSB would be at least mildly interested in these numbers.

And that's why Boeing informed them of this episode, they knew NTSB would be interested.
People are reading too far in to the legalistic word "unreportable".
It has a very specific legal meaning, followed by very specific paperwork requirements.
Trust me, if NTSB felt differently, they could and would insist on a formal reporting and Boeing would comply.

SheikhDjibouti wrote:
Their highly reliable, low maintenance 787 Dreamliner is more like an unreliable, high maintenance 787 Nightmare.
(ok, maybe I'm exaggerating there, but it's only poetic license) :D

QF's CEO tells us he can run two 787-9s tail to tail for less than one A380, and tells us it'd take a long drunken night to convince him to order A380+.
Guess he has the same license! :D
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dtw2hyd
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 2:23 pm

WIederling wrote:
" What are JCAB and JTSB doing? "
Moot. NTSB was actively involved and primary investigator in the path to the certification authority ( FAA ).


Is there any validity to your statement?

AFAIK, JCAB certified 787 battery system and FAA accepted JCAB's certification, just like EASA certified A350 Battery and FAA accepted(with some delay) EASA's certification.

So primary responsibility still lies with JCAB.

Revelation wrote:
SheikhDjibouti wrote:
I should imagine the NTSB would be at least mildly interested in these numbers.

And that's why Boeing informed them of this episode, they knew NTSB would be interested.


But if Japanese carriers were "proactively" changing out, those will never get reported because those are not reportable events and considered confidential to the company.
 
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 2:51 pm

dtw2hyd wrote:
AFAIK, JCAB certified 787 battery system and FAA accepted JCAB's certification, just like EASA certified A350 Battery and FAA accepted(with some delay) EASA's certification.


You are mistaken.
FAA, through its “authorized representatives”, certified the 787 battery system.
https://www.seattletimes.com/business/faa-boeing-delegated-much-of-787-testing/

Thales of France, which designed the battery system, was responsible for providing test data and paperwork to Boeing for certification.
But lacking any experience in certifying lithium-ion batteries, Thales in turn depended on the expertise of battery maker GS Yuasa of Japan, said Thierry Queste, a 787 project manager with the French company.

Boeing officials insisted that, despite the outsourcing to Thales of the design work for the first large lithium-ion batteries on a commercial airliner, its engineers maintained control.

“Boeing was involved and had complete oversight of the suppliers throughout,” senior Boeing systems engineer Jerry Hulm told the NTSB panel.

And FAA officials were equally adamant that their technical experts were “heavily engaged” in the 787’s certification.

However, the FAA oversight role portrayed by agency officials in many respects was indirect — almost like a back-seat driver, with Boeing up front — because of an enormous disparity in resources between the jet maker and its regulator.

The head of the Renton-based FAA certification office, Ali Bahrami, said he has 20 to 25 staff working full time on the 787. The entire airplane-certification division of the federal agency has fewer than 1,300 employees nationwide to cover at least six current new airplane-certification programs as well as ongoing airworthiness issues.


So the FAA relies in large part on 950 engineers who are paid by Boeing but work as FAA “authorized representatives” to oversee and approve the certification of the 787 and other Boeing jets.

It was such authorized reps who traveled to Japan to witness and sign off on GS Yuasa’s battery-certification tests.

“It would be virtually impossible to keep up with industry” without this extensive delegation of oversight to the manufacturer, said Dorenda Baker, director of the FAA’s national aircraft-certification unit.

The revelations came on the second day of an investigative hearing in Washington, D.C. The inquiry arose out of a battery fire on a 787 parked at Boston’s Logan International Airport in January, and an incident a week later when a smoldering battery in-flight forced an emergency landing and slide evacuation in Japan.
 
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SheikhDjibouti
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 3:27 pm

Revelation; I am so disappointed with your #223 post - it's not one of your finer efforts. :cry:
Firstly, you took a quote of mine out of context, and therefore gave an incorrect response, as follows;
dtw2hyd wrote:
One data point NTSB should investigate is how many 787 batteries/cells were swapped as part of "routine" maintenance by Japanese carriers

...and then I wrote:
I should imagine the NTSB would be at least mildly interested in these numbers.

Revelation wrote:
And that's why Boeing informed them of this episode, they knew NTSB would be interested

Neither dtw2hyd, nor myself, were talking about "this episode" and Boeing; that is a done-deal, and Boeing have been given credit (by some of us at least) for 'fessing up and voluntarily reporting the Paris incident (UA915).
Meanwhile dtw2hyd & myself were actually discussing battery swaps that may have happened without fire, smoke, or excessive venting, as part of "routine" maintenance by Japanese carriers, and thus not being reported. Such actions may have avoided potential problems, but void the specific claim some have made that these Li-Ion packs were better than Ni-Cads because they needed less maintenance.

SheikhDjibouti wrote:
Their highly reliable, low maintenance 787 Dreamliner is more like an unreliable, high maintenance 787 Nightmare.
(ok, maybe I'm exaggerating there, but it's only poetic license) :D

Revelation wrote:
QF's CEO tells us he can run two 787-9s tail to tail for less than one A380, and tells us it'd take a long drunken night to convince him to order A380+.
Guess he has the same license! :D

He might have that license, but you don't.
I was bemoaning the difference between the Dreamliner Boeing could've/should've built, and the reality of what has actually happened.
No mention of Airbus there, or indeed in my previous posts.
But you dragged us towards yet another "Boeing are better than Airbus" mud-slinging contest. Do you really want to go there..... again? I don't. :shakehead:
There are two things that happen when you get old.
1. You start to lose your memory.
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dtw2hyd
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 4:09 pm

mats01776 wrote:
It was such authorized reps who traveled to Japan to witness and sign off on GS Yuasa’s battery-certification tests.



Let me rephrase this sentence. "FAA reps witnessed tests and JCAB sign-off on GS Yuasa’s battery-certification". FAA cannot go into a different jurisdiction and certify. All CAAs of countries involved in aviation manufacturing have agreements to accept each others certification at face value.
 
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 4:23 pm

dtw2hyd wrote:
mats01776 wrote:
It was such authorized reps who traveled to Japan to witness and sign off on GS Yuasa’s battery-certification tests.



Let me rephrase this sentence. "FAA reps witnessed tests and JCAB sign-off on GS Yuasa’s battery-certification". FAA cannot go into a different jurisdiction and certify. All CAAs of countries involved in aviation manufacturing have agreements to accept each others certification at face value.


you will have to show some documentation to have us accept your rephrasing.
All the special conditions related to Li batteries on the 787 are FAA documents.

apropos what event in history are you talking about?

initial certification?
the battery burn in Japan?
no uncertainty about who handled the decomposition in the US.
Murphy is an optimist
 
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Revelation
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 4:37 pm

SheikhDjibouti wrote:
Neither dtw2hyd, nor myself, were talking about "this episode" and Boeing; that is a done-deal, and Boeing have been given credit (by some of us at least) for 'fessing up and voluntarily reporting the Paris incident (UA915).
Meanwhile dtw2hyd & myself were actually discussing battery swaps that may have happened without fire, smoke, or excessive venting, as part of "routine" maintenance by Japanese carriers, and thus not being reported. Such actions may have avoided potential problems, but void the specific claim some have made that these Li-Ion packs were better than Ni-Cads because they needed less maintenance.

Pretty much every reference I read says Ni-Cad needs maintenance every couple months, Li-Ion every couple years. It would take a lot of swapping to negate that, and even if it did, I wouldn't lose sleep over the fact that preventative swapping left someone's claim of low maintenance wanting. We know there are 600+ 787s flying and ~100 in Japan so we have 5x data points from non-Japanese carriers. In short, it's a vague statement with little correlation to facts on the ground. It rises no higher on the event spectrum than the fact that RR is proactively replacing T1000s in Japan and other places due to potential blade cracking, even though those engine swaps cause much more hardship and their failure can cause the kind of "reportable event" that many here find so worrisome.

SheikhDjibouti wrote:
SheikhDjibouti wrote:
Their highly reliable, low maintenance 787 Dreamliner is more like an unreliable, high maintenance 787 Nightmare.
(ok, maybe I'm exaggerating there, but it's only poetic license) :D

Revelation wrote:
QF's CEO tells us he can run two 787-9s tail to tail for less than one A380, and tells us it'd take a long drunken night to convince him to order A380+.
Guess he has the same license! :D

He might have that license, but you don't.
I was bemoaning the difference between the Dreamliner Boeing could've/should've built, and the reality of what has actually happened.
No mention of Airbus there, or indeed in my previous posts.
But you dragged us towards yet another "Boeing are better than Airbus" mud-slinging contest. Do you really want to go there..... again? I don't. :shakehead:

Interesting license that you can use yet the CEO of QF cannot.
You used it to drag us into "nightmare"-ish rhetoric and made a very broad claim based on one incident.
The reality of what is happening is 600+ 787s are in service now and making many customers such as QF quite happy.
It's hard to explain the reality of EK ordering 40 and production rate being increased if it was unreliable and high maintenance as you claim.
Now that they are in service, they are anything but a nightmare and draw positive comparisons from luminaries such as QF's CEO.
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Stitch
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 5:05 pm

WIederling wrote:
All the special conditions related to Li batteries on the 787 are FAA documents.


Correct, but those conditions were relayed back through the supply chain and local certifying authorities - in this case, the JCAB for GS Yuasa - signed off that those conditions had been met by GS Yuasa. The FAA then accepted JCAB's verification that the special conditions for that component had been met.
 
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 7:06 pm

enzo011 wrote:
scbriml wrote:
That 787 batteries continue to fail?


My only concern would be whether the batteries are failing earlier and with more frequency than was predicted. This I am sure will be investigated and if action needs to be taken I am sure the relevant safety authorities will publish the needed action.


Since Li-ion battery failure is no longer a safety issue on the 787, why should you or the relevant safety authorities be concerned about the reliability of the batteries?

dtw2hyd wrote:
Because NTSB is waiting for the promised permanent fix by the vendor.


The NTSB were clearly happy to sign off on the containment system regardless of any pending "permanent fix". Given the root cause of the failure was never identified, I suspect the NTSB is not holding their collective breath for the alleged permanent fix.
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iamlucky13
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 8:27 pm

kalvado wrote:
Blade out on engine - and that is scenario for engine shroud - is a reportable event, as far as I understand - especially on ETOPS flight


Right, because there are downstream risks even if the blade loss is contained, including from loss of thrust and the small but I don't quite zero risk of damage from lower speed "contained" debris.

If the manufacturer has provided compelling evidence to the regulators the battery containment and venting system addresses every downstream risk both parties can think of, the regulator doesn't have much reason to require reporting unless they start just making risks up.

And apparently the risks addressed does include both tests of the flammability of the evolved gases (in the absence of additional oxygen, due to the box), and "pressurization" if somehow those gases do ignite despite one of the three necessary fire ingredients being insufficient. I put pressurization in quotation marks, because from watching the video, that seems like verbiage a lawyer came up with for describing a contained explosion test.

Pressurization is at 2:32
https://www.youtube.com/watch?v=xaqQuBac2ag

I haven't yet been able to find technical reports on either of those tests, unfortunately.

enzo011 wrote:
My only concern would be whether the batteries are failing earlier and with more frequency than was predicted. This I am sure will be investigated and if action needs to be taken I am sure the relevant safety authorities will publish the needed action.


The point others are making is that without a reporting requirement, there's no assurance of further investigation by authorities. Whether that is an issue depends on whether the alternative means of compliance of containment and venting actually meets the safety criteria.

Revelation wrote:
Pretty much every reference I read says Ni-Cad needs maintenance every couple months, Li-Ion every couple years. It would take a lot of swapping to negate that


Boeing's original requirement was 5 year service life. Even if the lifespan is meeting its target, somewhere around 100 batteries could have been replaced so far, and because of the production ramp-up, if the real life is a mere 20% lower than spec'd, the number of replacements more than doubles.
 
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kanban
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 8:54 pm

SheikhDjibouti wrote:
but it still coming back to a BOEING problem?


Please understand that Boeing does not have the resources or knowledge to design everything on a plane. Frequently they put out specification requirements (the part size envelope, the function, the stresses, the output requirements etc). these are sent to established manufacturers with the knowledge and skills base to produce a design. if the designs are approved the leading one or two manufacturers the build and test the product. When Boeing is satisfied that the product functions and has the service life expected, they release contracts to build and supply. Since the initial failure was internal to the delivered battery pack, no amount of Boeing engineering or quality control would have identified it (yes they did find some crimped wires at one point, but that was a secondary issue). Boeing on-site personnel were contract types not engineers. So I find it difficult to assess blame to Boeing as so many wanted to do. The manufacturer had difficulty finding the problem cause and they were the experts.. and I believe that it was found to be component contamination.. new processes were brought into play to eliminate the issue. now we are seeing a one off battery failure that is more probably related to use and recharging than manufacture. One thing that you can be assured of is the battery and titanium box are on their way back either at Boeing or the manufacturer where a team will dissect them to see what happened.
 
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 9:00 pm

rheinwaldner wrote:
IIRC, the images of the battery showed that the cells did not even have some cell balancing capabilities. That's dilettantish. My hobby grade lipo charger for 50€ has it....


The 787 battery has cell balancing. In the video I linked to in my immediately prior post has a closeup at the start of it where you can see the many small wires between the battery management unit and each cell for cell-level voltage monitoring, temperature monitoring, and cell balancing, and the NTSB testimony by GS Yuasa confirms the BMU in the original battery also performed balancing.

Stitch wrote:
Okay. I don't know what the electrical needs for the A350 are, but maybe it's systems need as much juice as the 787's even though they are not electrically-driven.


I wish I'd been able to find more about this, since I also had the impression the A350 needed less electrical power than the 787. Even before the battery fire, Boeing had publicly disclosed a fairly impressive amount of information about the 787 electrical system, but I haven't yet found similar for the A350.

SheikhDjibouti wrote:
I've got 450A for 45s, which could indeed be the load profile, or a misprint, but let's not argue. That 10 minutes to re-charge is looking pretty rosy. And as you say; the APU start hasn't killed the battery in the first place. Total red herring.


My 650A figure is based on a test requirement of 18 kW load, and I think I assumed the battery was at 28V under load.

SheikhDjibouti wrote:
That 10 minutes to re-charge is looking pretty rosy. And as you say; the APU start hasn't killed the battery in the first place. Total red herring.


That specific reason being a red herring or not, it seems to me Boeing must have pretty strong reasons to stick with lithium ion in the long term, since they've had 4 years to certify an alternative if they so desired.

SheikhDjibouti wrote:
aviationtoday.com; 2013 wrote:
The failure analysis of the battery system on the 787 foresaw a battery thermal failure event as being something so rare it could be expressed in terms of once in 10 million flight hours, but actually one failure occurred within 196 flight hours, another within 2151 hours, a very troubling discrepancy of projected reliability. Many public statements claimed that the faults occurred after 52,000 flight hours, but this is not correct. That higher total was taken from the combined totals of all 50 aircraft in service and test flights.

Are they right, or are they wrong? (reminder; this was 2013)
Even if we take the figure of 52,000 hours for the combined fleet, it's hardly flattering.


Aviation Today seems to have incorrectly tried to portray the 52,000 hour figure as if Boeing was moving the goalposts. Even if an aviation reporter is for some reason not familiar with the typical way of quantifying risks as related to certification in the industry, it should have been clearly obvious to the author that the 10 million flight hour criteria is counted fleet wide just based on magnitude. No individual aircraft has, nor will within the foreseeable future come anywhere remotely close to 10 million flight hours (1142 flight years).
 
mats01776
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 9:23 pm

Stitch wrote:
WIederling wrote:
All the special conditions related to Li batteries on the 787 are FAA documents.


Correct, but those conditions were relayed back through the supply chain and local certifying authorities - in this case, the JCAB for GS Yuasa - signed off that those conditions had been met by GS Yuasa. The FAA then accepted JCAB's verification that the special conditions for that component had been met.

I have read through the NTSB report on the incident in its entirety.
https://www.ntsb.gov/investigations/AccidentReports/Reports/AIR1401.pdf
But, I could not find any indication that JCAB ever got involved in "local verification" of the Yuasa battery system during the initial certification of the 787.
NTSB/AIR-14/01. PB2014-108867. Notation 8604. Adopted November 21, 2014. Aircraft Incident Report. Auxiliary Power Unit Battery Fire. Japan Airlines Boeing 787-8, JA829J. Boston

1.6.1 Main and Auxiliary Power Unit Battery Development

Boeing required its suppliers and subtier suppliers to perform first article inspections (FAI), according to industry standards, on first production runs of any component. The FAI was the primary method for inspecting and testing vendor components and was considered to be an essential step in approving an order or a contract. The intent of the FAI was to determine if a vendor’s product met acceptance and quality control requirements to ensure that all engineering, design, and specification requirements were correctly understood, accounted for, verified, and recorded. GS Yuasa accomplished the FAI for the main and APU battery in November 2008, and Thales approved the FAI results in January 2009. GS Yuasa performed another FAI of the battery after its redesign resulting from the APSIF event. Further, in November 2010, Boeing performed an FAI on an LVP65-8-402 battery at GS Yuasa and found that the battery complied with acceptance and quality control requirements.
Boeing’s surveillance of Thales was conducted in accordance with contractual specifications and requirements. Boeing also relied on the Bureau Veritas Certification to perform surveillance assessments of Thales twice a year.84
Thales conducted two audits of GS Yuasa between the time that battery production began and the incident. These audits, which were conducted in June 2011 and September 2012, found 11 discrepancies, all of which were subsequently closed. None of the discrepancies were directly related to battery or cell manufacturing. Thales reported the results of these audits to Boeing.
Boeing did not conduct any audits of GS Yuasa before the incident and relied on Thales to audit its subtier suppliers.85 After the incident, Boeing sent an audit team to Thales and GS Yuasa (and KAI) to review the management of subtier suppliers, quality of manufacturing and business processes, and adherence to Boeing standards. The audit found 17 items of noncompliance with Boeing requirements. Most of the noncompliance items at GS Yuasa involved adherence to written procedures and communication with Thales and Boeing regarding authorization for proposed procedural and testing changes for the battery. The noncompliance items at Thales involved adherence to contractual requirements for Boeing’s approval on drawing or procedural changes. Corrective actions for all of the noncompliance items have been completed by Thales and verified by Boeing.
...
1.7.2 Certification Plan

FAA Order 8110.4, “Type Certification,” described the responsibilities and procedures for the FAA and the type certificate applicant to follow when evaluating and approving design data for new civil aircraft, such as the 787-8.101 In accordance with paragraph 2-11d(1)(d) of the order, Boeing’s 787 EPS certification plan presented a high-level system description of the EPS, which included the main and APU battery and battery charger system; defined the methods (for example, tests and analyses) to show compliance with applicable FAA and EASA requirements; and defined the compliance submittals (that is, certification deliverables) to be provided to the agencies. The FAA approved the initial certification plan on December 22, 2005. Boeing was required to ensure that the certification plan was kept current throughout the 787’s design, development, and certification phases, and any revisions to the certification plan were required to be approved by the FAA.

According to Boeing, on January 8, 2007, the FAA approved revision C of the certification plan and indicated that Boeing could proceed with the implementation of the proposed certification activities. Boeing conducted tests and analyses to demonstrate, among other things, that the main and APU battery and battery charger system complied with relevant 14 CFR Part 25 requirements, including sections 25.863, “Flammable Fluid Fire Protection,” paragraphs (a) and (b)(3); 25.1309, “Equipment, Systems, and Installations,” paragraphs (a), (b)(1), (b)(2), and (c) through (g); and Special Conditions 25-359-SC.


I would appreciate if you could direct me to the source of information that JCAB was involved in the initial certification of Yuasa batteries.
Thank you in advance.
 
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 9:58 pm

scbriml wrote:
The NTSB were clearly happy to sign off on the containment system regardless of any pending "permanent fix".


NTSB signed off on nothing.
NTSB reports on safety issues.
FAA is the regulatory authority.
But they also have the "further US aviation" job. This competes with their regulatory job and taints it.

My guess would be that the NTSB was unhappy and stays unhappy.
Murphy is an optimist
 
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enzo011
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 10:24 pm

scbriml wrote:
Since Li-ion battery failure is no longer a safety issue on the 787, why should you or the relevant safety authorities be concerned about the reliability of the batteries?



When I say I, I mean to say the only thing I think the safety authorities may look at is the rate of failure of the batteries and if they correspond to the figures that was thought during certification. Now I am going on memory here but the rate of failure Boeing said could happen was so infrequent that they would be practically non-events when it did happen. When a couple failed so close to each other this changed people's view on those failure rates and whether it is just non-events so it needed to be investigated.

Now this failure may or may not be of concern. I don't know and its good that its reported to the authorities. If this failure was as predicted before 2013 then nothing to see here, if this is a more frequent occurrence then I am sure an AD will be issued to address the problem.
 
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Stitch
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 10:39 pm

enzo011 wrote:
scbriml wrote:
Since Li-ion battery failure is no longer a safety issue on the 787, why should you or the relevant safety authorities be concerned about the reliability of the batteries?


When I say I, I mean to say the only thing I think the safety authorities may look at is the rate of failure of the batteries and if they correspond to the figures that was thought during certification. Now I am going on memory here but the rate of failure Boeing said could happen was so infrequent that they would be practically non-events when it did happen. When a couple failed so close to each other this changed people's view on those failure rates and whether it is just non-events so it needed to be investigated.


The reason the safety authorities now require the current containment systems on the 787 is because the batteries did not fail in the ways predicted for effect and timescale as allowed for the original, less-robust containment system. So the containment system was strengthened to account for these more volatile and violent failures. So provided the containment system is working as designed and keeping any future battery event within safe parameters, the safety authorities should be satisfied.

Who won't be satisfied if the contained failure rate is too high are the operators - on financial grounds, not safety.
 
WIederling
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 10:39 pm

".. why should you or the relevant safety authorities be concerned about the reliability of the batteries?"

Their reliability is still required for the engine out emergency landing procedure.
It is not sufficient to do that final landing without spewing flames all along.
Murphy is an optimist
 
dtw2hyd
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 10:58 pm

WIederling wrote:
".. why should you or the relevant safety authorities be concerned about the reliability of the batteries?"

Their reliability is still required for the engine out emergency landing procedure.
It is not sufficient to do that final landing without spewing flames all along.


Because batteries are inside the aircraft. Make them ejectable.
 
QueenoftheSkies
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 11:04 pm

scbriml wrote:
WIederling wrote:
This
and the apparent corollary that nobody or the NTSB has any further interest in why they fail.


If they are failing safely, the containment is doing its designed job and there is no threat to flight safety, why should they have further interest in why they fail?

It seems to me it's no longer a safety issue, but one of reliability. In that case Boeing and Yuasa should be far more interested than the safety boards or certifying authorities.

It is absolutely a different kettle of fish if containment fails. :yes:


Failing safely? If that’s not contradictory I don’t know what is. Why should they further invest? Umm maybe so that they don’t fail in the first place? I mean yea the containment works but that’s a bandaid to the real issue. They never really solved the problem. It’s not a safety issue? Potential for repeat incidents of what caused this containment “solution” are most definitely a safety issue.
 
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 11:25 pm

QueenoftheSkies wrote:
Failing safely? If that’s not contradictory I don’t know what is.


"Fail safe" is a common enough term and is certainly not contradictory. :shakehead:

https://en.wikipedia.org/wiki/Fail-safe

QueenoftheSkies wrote:
Why should they further invest? Umm maybe so that they don’t fail in the first place? Potential for repeat incidents of what caused this containment “solution” are most definitely a safety issue.


That's a reliability and cost issue for Boeing and Yuasa. With the containment in place, it's no longer a safety issue as far as the certifying authorities are concerned.
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hivue
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 11:32 pm

[quote="QueenoftheSkies]Failing safely? If that’s not contradictory I don’t know what is[/quote]

Fail safe is a common engineering practice. We do not inhabit a perfect universe. Things will go wrong and we have to plan for that and implement strategies to mitigate the bad consequences.

It's often said the flying is the safest way to travel. But hurtling along in an aluminum and carbon fiber and kerosene-laden tube 30 or 40 thousand feet in the air at 500 kts is by far the most dangerous thing most of us ever do in our lives. The wonderful safety statistics are due to processes and procedures carefully developed for designing, developing, testing and operating aircraft.
"You're sitting. In a chair. In the SKY!!" ~ Louis C.K.
 
iamlucky13
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 11:45 pm

QueenoftheSkies wrote:
scbriml wrote:
WIederling wrote:
This
and the apparent corollary that nobody or the NTSB has any further interest in why they fail.


If they are failing safely, the containment is doing its designed job and there is no threat to flight safety, why should they have further interest in why they fail?

It seems to me it's no longer a safety issue, but one of reliability. In that case Boeing and Yuasa should be far more interested than the safety boards or certifying authorities.

It is absolutely a different kettle of fish if containment fails. :yes:


Failing safely? If that’s not contradictory I don’t know what is. Why should they further invest? Umm maybe so that they don’t fail in the first place? I mean yea the containment works but that’s a bandaid to the real issue. They never really solved the problem. It’s not a safety issue? Potential for repeat incidents of what caused this containment “solution” are most definitely a safety issue.


It's not at all contradictory. Failure and safety are often related, but not equivalent.

Safe failure is a very common engineering concept. There are myriad situations where a failure can not be precluded, so a failure modes and effects analysis (FMEA) is done to figure out what happens as a result, and therefore what needs to be mitigated.

You can have failures that do not by nature affect safety (the in flight entertainment not working, for example), or failures that can potentially affect safety but are mitigated to stay within the safety criteria.

For the 787 battery system, the criteria is preventing heat damage to other systems or the structure, or accumulation of hazardous fumes or smoke. The battery failing in the prior configuration could not be demonstrated to comply with those criteria. Enclosed in the containment box and vented, it can.
 
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Re: Lithium-ion battery fails on UA 787 flight

Thu Dec 07, 2017 12:18 am

WIederling wrote:

Their reliability is still required for the engine out emergency landing procedure.
It is not sufficient to do that final landing without spewing flames all along.


If you're talking about a single engine out landing, except for the fact that the battery is required for flight in general it provides no extra assistance.

If you're talking about a dual engine failure, there are no emergency landing procedures. However after a dual engine failure the main battery will provide power to the captain's flight instruments until the RAT comes online and should you find a field conveniently close to land at the fact that it would provide power to stop the airplane is just gravy.

If the battery reliability was as bad as some indicate we'd have heard about it.
 
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Re: Lithium-ion battery fails on UA 787 flight

Thu Dec 07, 2017 5:17 am

dtw2hyd wrote:
WIederling wrote:
".. why should you or the relevant safety authorities be concerned about the reliability of the batteries?"

Their reliability is still required for the engine out emergency landing procedure.
It is not sufficient to do that final landing without spewing flames all along.


Because batteries are inside the aircraft. Make them ejectable.

how would you like one to land on your car or house????
 
WIederling
Posts: 4642
Joined: Sun Sep 13, 2015 2:15 pm

Re: Lithium-ion battery fails on UA 787 flight

Thu Dec 07, 2017 9:10 am

dtw2hyd wrote:
WIederling wrote:
".. why should you or the relevant safety authorities be concerned about the reliability of the batteries?"

Their reliability is still required for the engine out emergency landing procedure.
It is not sufficient to do that final landing without spewing flames all along.


Because batteries are inside the aircraft. Make them ejectable.


Brilliant idea, man.
The battery is required for an engine out landing. ( from below "RAT effective" speeds to a standstill.)
for that contingency case a contained battery fire or ejection is not the way to go.
Murphy is an optimist
 
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747classic
Posts: 2270
Joined: Sat Aug 15, 2009 9:13 am

Re: Lithium-ion battery fails on UA 787 flight

Thu Dec 07, 2017 12:46 pm

The main battery provides backup power for critical systems during flight in the extremely unlikely event of a total electrical power failure.(e.g.all six generators unable to provide electrical pwr), it's a certification requirement.

The main battery is not mentioned in the 787MMEL, so must be servicable before any departure.

Seen the history of 787 main battery issues It should have been SOP to report the main battery failure frequency to the FAA and the NTSB

If the 787 main battery failure rate is significant higher than on other airraft types (only Boeing knows !!), I would prefer not to be on board of a 787 with a main battery burn out in the middle of an ocean crossing.
Statistical note : The odds of a total electrical failure remains the same after a main battery failure.
Operating a twin over the ocean, you're always one engine failure from a total emergency.
 
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enzo011
Posts: 1471
Joined: Tue Jun 21, 2011 8:12 am

Re: Lithium-ion battery fails on UA 787 flight

Thu Dec 07, 2017 12:48 pm

Stitch wrote:
The reason the safety authorities now require the current containment systems on the 787 is because the batteries did not fail in the ways predicted for effect and timescale as allowed for the original, less-robust containment system. So the containment system was strengthened to account for these more volatile and violent failures. So provided the containment system is working as designed and keeping any future battery event within safe parameters, the safety authorities should be satisfied.

Who won't be satisfied if the contained failure rate is too high are the operators - on financial grounds, not safety.



Has the failure rate calculations changed from when the 787 was certified? Or are they still predicting the failures at the rate as before the 2013 problems?
 
dtw2hyd
Posts: 4988
Joined: Wed Jan 09, 2013 12:11 pm

Re: Lithium-ion battery fails on UA 787 flight

Thu Dec 07, 2017 1:09 pm

WIederling wrote:
dtw2hyd wrote:
WIederling wrote:
".. why should you or the relevant safety authorities be concerned about the reliability of the batteries?"

Their reliability is still required for the engine out emergency landing procedure.
It is not sufficient to do that final landing without spewing flames all along.


Because batteries are inside the aircraft. Make them ejectable.


Brilliant idea, man.
The battery is required for an engine out landing. ( from below "RAT effective" speeds to a standstill.)
for that contingency case a contained battery fire or ejection is not the way to go.


What good is a toasted main battery in a box?

Maybe 787 should have a generator in the wheel to pick up from where RAT quits. Or EMAS to the rescue.

We can go in circles forever, but GS Yuasa, JCAB and JTSB are more culpable than Boeing, Thales, Securplane, FAA, NTSB, BEA and other airlines.
Last edited by dtw2hyd on Thu Dec 07, 2017 1:35 pm, edited 1 time in total.
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