Heathrow B-787 fire report released.

[BEagle]

The full report in to the Ethiopian Airlines Boeing 787 fire at LHR in July 2013 has now been released:

https://assets.digital.cabinet-offic...015_ET-AOP.pdf

[OldLurker]

Wires trapped under the ELT's battery compartment cover-plate seem to have chafed and caused a short-circuit which caused thermal runaway failure of a cell in the Li-MnO2 battery. There were cell-level and battery-level safety features but they didn't prevent this single-cell failure, which propagated to adjacent cells, resulting in a cascading thermal runaway, rupture of the cells and consequent release of smoke, fire and flammable electrolyte. And off it went.

Plus, as usual, other factors: design of the ELT, its location in the aircraft, safety assessment for the ELT certification didn't identify battery failure modes, etc.

I think we know quite a lot more about lithium batteries generally now, and every competent manufacturer and operator is being a lot more careful.

[MrSnuggles]

Thankyou very much, BEagle! I was waiting for this one! It was a very interesting thing to see the damage and the following repair job - the few photos that captured this.

In short, the summary concludes that Li-battery thermal runaway in a faulty ELT and slow burning resin from the composite materials contributed to the damage.

I wonder why Li-batteries aren't banned on aeroplanes. There is always the "WHAT IF..." factor with those things. I read the report from the 747 cargo flight downed by Li batteries.. extremely unsettling reading. Thank Gods there was noone on board this plane!

[DaveReidUK]

Do yourself a favour and have a look at the report - pages 13 - 15 - and I am sure you will find the info informative.

The 15 Safety Recommendations (P142-146), including those made early in the course of the investigation, are also worth reading.

[BEagle]

MrB, the frown is because someone clearly wasn't capable of installing the battery pack correctly and securing the cover plate properly. As a result the wires were trapped and chafed, causing a short circuit, battery fire and the release of toxic fumes through the gap in the plate....

That such a botched job could have caused such damage is surely of concern.

[MrBernoulli]

Beags, yes, of course, the causes are concerning, but sadly that is the world we work in - one which relies on so many humans doing their bit correctly so that we may fly safely. Never mind the folk who positively want to do us harm.

Sorry, my question was because I thought there was something specific in this particular incident that caused the . I acknowledge that any fault, be it technical or human, is a worry.

[Volume]

every competent manufacturer and operator is being a lot more careful.

because of the poor publicity such events produce. I think the competency has been there before, probably now also the funding and the will to change is available..

And I really love the british understatement...

A fire within the fuselage of a passenger aircraft can present significant survivability issues.

[PiggyBack]

Failure to handle short circuit is significant

What I find more interestingis the failure of the pack to handle a short circuit safely. The use of a PTC for this is very common but the variability of trigger point and it's dependance on environmental conditions make it tricky to be sure it will protect and quite likely that short circuit protection could be successfully tested yet a catastrophic failure is still possible. The normal way this is tested is simply to introduce a dead short and check it is handled adequately. resistive or intermittant short circuits which are critical to how the battery pack could fail despite PTC protection are not tested.

A battery short circuit is a very obvious failure mode which any design should handle as this battery pack was clearly intended to.

We have designed many medical devices with simlar packs and PTC protection although we usually have an additional safety device on the battery so it is a concern that such a pack failed in this way even if we have another layer of protection beyond that used in this case.

[farefield]

Assembled at Everett too,they can't even blame Charleston.

[aeo]

When this incident first occurred I seem to remember the experts saying that had it been an aluminium fuselage aircraft it would've burnt to the ground . . .

[Volume]

I am not sure about that statement. If it had been an 30 year old typical design (including the aluminum fuselage), it would´ve burnt to the ground. I think people have learned a bit about insulation since SR111... And they were probably extra careful for a composites fuselage.

[Rob Bamber]

Relevant to MH370?

This morning I read this article in the Guardian. This afternoon I wondered whether it could explain MH370. The Guardian wrote

At the time of the Heathrow fire, there were an estimated 3,650 identical RESCU 406AFN ELT batteries in service, fitted to numerous aircraft types

And also

Had the aircraft been in flight, the location of the ELT, which was above ceiling panels at the rear of the passenger cabin, meant crew or passengers would not have immediately noticed the fire. “It is not known how long it may take for such a fire to be detected and the location of the ELT could prolong the time taken to locate the source,” the report said.

Is it possible that such a fire on MH370 could explain the incapacitation of the crew and PAX, and also the deactivation of the transponders?

This is a question from me, not a hypothesis.

[vapilot2004]

Is it possible that such a fire on MH370 could explain the incapacitation of the crew and PAX, and also the deactivation of the transponders?

Doubtful. SATCOM transciever was on, indicating AC power was available for the many hours after the aircraft went silent. The course changes made post-silence also suggest the aircraft was under the control of a thinking, conscious human. Finally, the transponder wiring, antennae, LRUs, and control head are literally on the other end of the aircraft from the tail-mounted ELT.