Swedish Steve
“Fuel pump switch position is recorded.
Fuel pump output pressure switch sense is recorded.”
Thanks for that. If this is the case and the FDR shows no switch selected on and no pump outlet pressure at the end of the flight, then I reckon this rules out my centre tank feed theory. Do you have a full list of ATA28 FDR parameters? How about a schematic? Training notes?
PAXboy
“We learnt that 777 standard procedure is to use the Centre tank fuel first and it it's entirety. Any fuel remaining in CT is then scavenged out to the wing tanks. The rest of the flight is supplied from each wing tank to it's respective engine. (Presumably for better trim?)”
It’s not SOP, it’s system design. The SOP is to select all tank pumps on before engine start, I expect. With all pumps on, the system feeds from the centre tank first by design. The reason for using centre tank fuel before wing tank fuel is for wing bending moment relief.