Originally Posted by
excrab
I only have experience of one company’s ETOPS requirements on the NG so it’s not definitive, but we couldn’t dispatch an ETOPS flight unless both engine generators and the APU generator was serviceable. In flight the APU had to be started prior to the ETOPS entry point and if it didn’t start or one of the engine driven generators failed prior to the entry point then we had to re-route to ensure we remained within one hour of a suitable airfield. I would imagine that would apply to most ETOPS aircraft unless they have a RAT that can provide sufficient power if one of the other sources fails.
One genarator is MEL-able for ETOPS (120min) in EASA land at least. I remember a different kind of incident though on a classic, where the battery would not charge. The flight was going oceanic and at around TOC they turned back ( all generators good), but yet the main battery was pretty drained when they landed from a visual approach. They were losing a lot of instruments, radios, VHFNAV etc. Don´t remember what was considered cause.