Lithium Batteries
 

Have there been any instances of lithium battery issues on 787?.

Just Google for 787 lithium battery

See
https://www.pprune.org/rumours-news/...nt-ground.html
https://www.pprune.org/rumours-news/...unds-787s.html
and also https://en.m.wikipedia.org/wiki/2013...iner_grounding

but what you really want to know is whether the issues were fixed
an absence of accidents since 2013 suggests they were

Battery failures, while not ideal, are hardly uncommon on aircraft. The 787's were unusual because they resulted in fire not just a loss of power.

I am sure 'flight without batteries' is something demonstrated in the test campaigns and failure analyses.

You would find this thoroughly debated if you read/searched the now-locked accident threads.

There is a popular myth that - after the early 787 Li battery fires - all Boeing did was put the battery in a steel box and left the rest of the system alone.
That's a myth - a popular, often repeated myth - but still very much a myth.

In the aftermath of the original Li fires (and the associated grounding), Boeing and YUASA did a complete redesign - upgrading the charging system and the battery itself. However, due to the extent of the damage to the fire involved batteries, it was impossible to definitively determine the root cause - so in a bit of a 'belt and suspenders' approach, they put the redesigned battery in a stainless-steel box that would vent any fire or resultant toxic gases overboard. The intentionally caused a battery short-circuit to cause the battery to thermally runway in the steel box and verified that the box prevented the resultant fire from propagating out of the box.

Since the redesign, there have been a handful of single-cell battery failures, but none have propagated and spread to the rest of the battery.

It should be noted that there were two battery fires with only 50 aircraft in service for about a year. Since the redesign, there are over 1,000 787s flying around daily - racking up something like 30 million flight hours - without a reoccurrence of a battery meltdown.

And as I've posted repeatedly in the (now closed) threads, even with a 100% aircraft power loss, the engines are sufficiently isolated and independent that they will still operate just fine, so long is there is fuel in the tanks.

However
 

If the batteries, though inside a fireproof enclosure go off line, there is no starting the APU. Isn't the APU a requirement for ETOPS? Difficult to shrug off the EMER battery system due to merely mitigating risk of onboard fire? FAA quantifies an onboard fire as a one in a billion ? The box is an acknowledgement of an increased risk of fire? No resolution of what caused the battery issue? Though contained, is it not yet a fire? Has FAA altered the language in the rule? To make an exception for "well contained fire"?

A venting battery is not necessarily a fire. I suspect you'd also find that electrical issues are still the cause of more fires than the batteries. The A350 has quite similar batteries, containers, and venting arrangements, but from SAFT. More total capacity (4x50Ah vs 2x75Ah), too.

As tdracer states, going from two fires in 50 planes to no fires in a thousand is a pretty strong indicator that the original issues were fixed.


The 787 APU can be MELed for ETOPS up to 180 minutes (see MMEL, search for auxiliary). It's required to be running on the 737 (not just present/serviceable except in some parts of FAA-land) largely because there is no RAT, and battery starting an APU is not reliable. You can start the APU off any running (non-RAT) AC power source, not just the battery. Using ground power or an engine generator to start the APU will improve battery life.

(edit: note also that the ATR is approved for 120-minutes ETOPS despite not being fitted with an APU at all)

Virtually everything that runs on the battery gets recovered when the RAT deploys, and the flight controls (and maybe ISFD? not sure.) have their own dedicated batteries.

The big one that would worry me is that it appears all four electric brake controllers get their from either aircraft normal power or the main battery. If you had a total AC loss (perhaps due to fuel exhaustion), AND the main battery failed, I'm not sure you would be able to stop once the RAT stalls.


A running engine (or APU) sounds like a good example of a 'well contained fire' to me.

Yes, there have.