Written by Red Paddy in post:
In the case of an electrical failure, there should be a systematic shut down of systems-ie non essential items first. Would ACARS fall into the bracket of a non essential item? Would the fact that it kept transmitting faults until a final catastrophic conclusion to the events(as indicated by the cabin v/s message) indicate a random shutdown of systems in a progressively deteriorating situation? Also there has been a suggestion that the on board mobile phone system continued to operate.
To me there is only one thing that could cause a shutdown that would leave non essential items operating while essential items such as the ADIRU's and ISIS shut down and that would be a fire in the avionics bay knocking out essential systems in an erratic manner and not shutting down non essientials first.
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Exactly along the lines of what I have been thinking. On page 7 in this thread it is mentioned that ACARS is powered from AC1, and that it would be unpowered in an EMER ELEC CONFIG. That would indicate that the elctrics were working as long as the ACARS was transmitting, all the way until the vertical speed waring.
The flight controller computers are located away from eachother, so a single fire should not take out all of them.
So, if there is power, and at least some of the FCC's are working, what about the inputs (and outputs)? If all the sensors started to report conflicting information, how would that affect the computers? If there was not enouh consistant data to know what data to ignore.