AndiKunzi:
The RAT on the 777 can't power all the aircraft systems. It only supplies power to a few essential systems, such as the Capt and FO flight instruments and the flight control power supply assemblies. The autopilot is not considered essential and is not powered by the RAT.
As stated on p33 of the ATSB report, the assumption is that one engine flamed out first, followed by the second, resulting in a loss of power to both AC busses. At that point, the flight control system would have reverted to a degraded mode, the autopilot would have disengaged and 'if there were no control inputs then it would be expected that eventually a spiral descent would develop'.
When operating in a degraded mode, the flight control system has no envelope protection, i.e. no stall, overspeed, overbank protections, etc.
Last edited by BuzzBox; 27th Jun 2014 at 12:37.