Quoting najavens:
I have been informed by a collegue in Flight Safety, who has contacts with the AAIB, that they are currently running with the idea that there was fuel starvation to both engines. It seems that only 10% of the fuel required was making it to the engines causing them to wind down. The problem however is identiying the part of the fuel system at fault.
I believe that it is rare for a fuel system to be compromised by RF as there are mechanical systems as back-up, and I believe there are 2 FCU’s on the aircraft, one for each engine. For both to be affected by RF would be unusual.
1. Identifying the parts:
The parts most suspect IMHO, are of electro-mechanical composition and the mechanical part(s) of this hybrid design are the first components one finds in the engine fuel feed system, upstream from the engines toward the fuel tanks, the spar valves. They only have 2 positions: open or closed. These mechanical parts in the engine fuel feed lines are nothing but slaves to what the electrical parts, the control relays, of this "symbiosis" instruct them to do.
The electrical parts of this hybrid design are buried deep inside the aircraft's hull, nowhere near their mechanical "slaves." If for whatever reason these electrical parts were to be disrupted in their normal functioning and moved their mechanically slaved "other half" from open to closed position, starvation of fuel to both engines would be guaranteed.
Just a theory until proven by facts of course but if they were affected, i won't dare speculate as to what the source of the disruption could have been. Maintenance issues? Items carried on board, alien to the aircraft's systems? Were such items located in the passenger cabin or perhaps in a cargo hold? The list of possibilities could be long . . . . . and the possible causal source a needle in a hay-stack.
2. Mechanical back-up:
With reference to mechanical systems as a back-up in the fuel system, i would not be so sure about that. See my first comment above, "identifying the parts."
3. Both engines:
Too much emphasis is put on RF affecting both engines, this has already been discounted by the AAIB report which confirmed FCUs and EECs functioned as advertised. What ever the source of the disruption, if it could have potentially affected parts of the left and right engine fuel feed systems, especially when in close proximity to eachother in a confined space, the electrical parts mentioned in my first comment above would be very likely candidates in the chain of events resulting in the generally perceived theory of a common source failure (they meet close proximity and confined space criteria, making them perhaps vulnerable to a single, yet to be defined, causal source).
Green-dot