captjns
I assume that the proposed two hour limit (ETOPS 120) is based upon the reliability (or lack thereof) of the APU as an alternate source. The safety issues have been addressed with the fireproof box. But at this point, I don't see how anyone can derive useful reliability numbers when the root cause of the problem is not understood.
I find it interesting that the FAA and Boeing are both talking about safety issues having been fixed (the battery not burning a hole through the bottom of the atrcraft). But its the NTSB that is looking into the cause. And following from that, systems reliability.