FAA Grounds 787s

[joy ride]

From the sound of it the containment worked exactly as intended. This is fairly reassuring but I would be happier if Boeing and its suppliers fully understood what caused the problems and found a genuine solution. As things stand I think this problem could recur occasionally, which was exactly what I thought when they revealed the Containment System last year.

[Romulus]

Originally Posted by msbbarratt

On Tuesday, Japan Airlines said maintenance engineers who were in the cockpit saw white smoke from the cockpit. When they went outside the aircraft the smoke had dispersed. On returning to the cockpit the engineers found warning lights indicating possible faults with the main battery and charger.

The sequence of events is interesting:
Observable smoke
The passing of some seconds (at least), during which the smoke clears
Then the dashboard lights up with fault indicators.
It's good that the dash did light up, but the engineers still noticed the problem before the aircraft's own systems did. Good to see the engineers had their eyes open and paying attention to detail.

Need to be a bit pedantic here, because that's not quite what it says MSB.

There is no indication of when the dashboard lights lit up, only when the engineers noticed them.

[Torquelink]

So is this to become the new norm now?

Are there are such compelling reasons to retain these batteries that, henceforth, we will accept that one catching fire occasionally is as much a part of standard ops as an oil leak or worn tyre? The occasional fire on board a longhaul aircraft - properly contained of course - is just a routine incident and we just change out the battery and carry on?

If so, it's truly bizarre.

[Fostex]

Maybe bleed air isn't such a bad idea afterall!

[Kerosene Kraut]

Biggest and earliest operators.

[ironbutt57]

Been wondering the same thing Gobona...

[Self Loading Freight]

The NTSB update is interesting, especially in juxtaposition with this latest lively lithium incident. An announcement that "we'll be wrapping up the data gathering in March, and then get on with writing the report" must mean "and we've not found any urgent safety action points yet" - assuming that if the smoking gun had been found, some more timely interim advisory would have been issued.

Meanwhile, the bleeders continue to get toasty.

From which, one deduces:

1. The NTSB still doesn't know the ultimate cause of the failures
2. The stated March deadline is now likely to be extended
3. They're happy that the Boeing containment fix is adequate to ensure a/c safety
4. We've still got no idea when the no smoking rule for Dreamliners is likely to be enforced

The saga drags on...

[Ian W]

Originally Posted by GobonaStick

Any reason why only the Japanese aircraft seem to be suffering? Is there something they're doing which none of the others are doing? Or just an unhappy coincidence?

It was one of the questions that was asked way back down in the thread. Certainly, the 787 has been flying in increasing numbers and so far the other operators have not had an issue with the batteries (other items yes).

One would hope that the audit trail and archived data on each battery would show if anything unexpected was being done to/with the battery due to different procedures.

[fenland787]

I would expect that as part of the battery system redesign a lot more battery data is being logged so perhaps this latest incident will give more clues as to the root cause of the cell failure.

[llondel]

If you can't provide a good explanation for all the observed failures then you haven't fixed the problem and it will come back to bite you in the future. This is a general rule of thumb, not just applicable to the batteries.

[Porrohman]

Last March, in the comments section of an article in Aviation Week was the following comment;

Bayanist
1:55 PM on 3/29/2013
I guarantee that the 787 problem is not with the battery technology but with the assumption that it is possible to charge as many as 8 cells in series without problems. The weakest cell WILL reverse polarity and appear as a short after the fact. This is true for any battery technology. I have done it with diehard lead acid batteries. To be safe each cell must be charged individually. Otherwise it is similar to pushing a chain. Unless each link is PERFECTLY aligned there will not be success. Unless each cell is PERFECTLY matched there will not be success. Since this is clearly impossible in this universe there will be future problems unless my warning is heeded. Time will prove me correct, Of that I am certain. Watch and see!

Source; 787 ETOPS Threat Dismissed As Speculation

I'm not sure whether the battery redesign changed this aspect or not. If it didn't then perhaps this is the cause of the issue?

[tdracer]

There may actually be some good news here.
The previous events involved complete meltdowns of the batteries - leaving little evidence of the original failure mode.


This failure was isolated to a single cell with limited damage. With the battery largely intact it may be possible to determine the elusive root cause.

[repariit]

Bayanist
1:55 PM on 3/29/2013
I guarantee that the 787 problem is not with the battery technology but with the assumption that it is possible to charge as many as 8 cells in series without problems. The weakest cell WILL reverse polarity and appear as a short after the fact. This is true for any battery technology. I have done it with diehard lead acid batteries. To be safe each cell must be charged individually. Otherwise it is similar to pushing a chain. Unless each link is PERFECTLY aligned there will not be success. Unless each cell is PERFECTLY matched there will not be success. Since this is clearly impossible in this universe there will be future problems unless my warning is heeded. Time will prove me correct, Of that I am certain. Watch and see!

I do not doubt that this is true, but can anyone explain why we have not heard of such problems with lead acid or NiCad systems? There are scads of 24 volt systems of all battery types in aircraft, marine, and ground transportation equipment, all of them having 12 cells in series.

[no-hoper]

Aha.What about 20 cells in series ?

[Lemain]

I guarantee that the 787 problem is not with the battery technology but with the assumption that it is possible to charge as many as 8 cells in series without problems. The weakest cell WILL reverse polarity and appear as a short after the fact. This is true for any battery technology.

It's bollocks, actually, as everyone with a car knows. Where the battery technology is very sensitive to reverse polarity a shunt diode is placed across the cell. Anyway none of this is an acceptable reason for fires and fumes. Back in the '70s during an industrial work experience period I used to test packs of NiCds for military (airborne guided weapons) applications. We had to temperature cycle and fully charge the batteries several times from +100C to -55C. In several months in the lab/production I never heard of smoke or flames....quite a few didn't meet performance criteria after a couple cycles, which is why we cycled but no dangerous stuff. Most rechargeable cells are not so very sensitive and will tolerate a reverse polarity provided the power dissipated is not beyond certain limits.

[Lemain]

Aha.What about 20 cells in series

Potentially a higher reverse polarity. If that's a problem - and it's current, not voltage - then they clamp with a shunt diode. A Schottky diode is the most usual. It's not new technology.

[Porrohman]

I do not doubt that this is true, but can anyone explain why we have not heard of such problems with lead acid or NiCad systems? There are scads of 24 volt systems of all battery types in aircraft, marine, and ground transportation equipment, all of them having 12 cells in series.

The energy density of Lithium Ion batteries is much higher and the charging time is much less.

[no-hoper]

Aha again.All aircraft NiCd batteries i replaced/repaired had 20 cells in series
to provide 24V.

[Porrohman]

Aha again.All aircraft NiCd batteries i replaced/repaired had 20 cells in series to provide 24V.

Lithium Ion batteries have certain attributes that make them potentially dangerous in certain circumstances. Wikipedia isn't always infallible, but a read of the safety section of this article will give you an introduction to the peculiarities and risks of these batteries; Lithium-ion battery - Wikipedia, the free encyclopedia

[Airclues]

It's worth watching the first part of this FAA film about lithium ion batteries;

FAA In Flight Laptop Fires - YouTube