The Inspector wrote:
That makes zero sense, since ETOPS deals with the ability of the aircraft to reach a distant airport on one engine inoperative. .
It's been a while for me dealing with ETOPS but I'm sure you know better that Inspector. As you say it deals with the ability to reach a distant airport. That means ETOPS deals with anything that influences that, and a key area is fire suppressant systems. The hold, and this case battery fire suppressant and containment systems must be able to demonstrate the ability contain/suppress a fire for the same amount of time that the aircraft has to remain aloft for. I suspect if the FAA is pegging this back to 2 hrs then they don't have faith/ Boeing can't demonstrate the system is capable if this.