''That's not correct in this instance. The RAT wasn't deployed as, initially, they still had electrical power. One of Sully's masterstrokes was to start the APU almost immediately after the bird strike, so they never lost electrical power. They remained in Normal Law and had High AoA protection. It's one of the things which saved them.''
I just read the report. It appears the high pressure section on at least one of the engines was still running fast enough for the IDG to produce enough power to keep the electrical system in a normal configuration. If both engines had completely failed, there wouldn't have been enough time to start the APU to prevent the RAT deploying. It takes about 40 seconds for the APU to be available after initiating a start, the RAT would have deployed immediately on loss of both AC busses.
Interestingly, all three hyd systems were available until touchdown.
Last edited by Dan Winterland; 14th Jul 2012 at 08:57.