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.
Last edited by Someone Somewhere; 1st July 2025 at 12:29.