As posted by infrequentflyer789:
The 777 is ARINC 629 bus, which is multi-transmitter (and more advanced than anything other big jet until you get to 664 / AFDX on the A380 / 787), which should provide a lot of help with this issue.
The 777 FDR receives and stores selected parameters from various systems and sensors (to know which parameters must be equivalent to drawing Excalibur from the stone). A digital flight data acquisition function (DFDAF), part of the airplane information management system (AIMS) receives all the flight recorder data. The data from the systems is received through ARINC 429 and ARINC 629 data buses, and also analog signals and analog discretes. The DFDAF processes this data (converts it to a digital format) and sends it to the FDR through ARINC 717 data buses.
As posted by Backoffice:
I see this ice, whether it be from water in the fuel or the result of condensation being a sudden release, either due to temperature, flexing of the wing or vibration, of ice which has frozen and adhered to internal wing surfaces during the flight.
Most likely (if water sumping was correctly performed) there would not be that much ice adhering to the internal wing structure after a 20 hour downtime with temperatures between +6C and +11C before the flight to Beijing on Jan. 16. Add to that the 2 day maintenance downtime (inside a hangar?) before the flight to/from Shanghai on Jan. 14-15, where likely water draining and refueling would have taken place only hours before departure to Shanghai. Outside temperatures at Heathrow were between +4C and +11C on Jan. 12 thru 17.
It seems to me that whatever amount of water was present in the tanks during this period with ground times of 48 hours and 20 hours respectively, most of it, if present, would have been drained. In addition, refueling at Heathrow (according to the AAIB) occurred only
after sumping for water, any condensation adhering to the interior structure (water, not ice with so many hours of temps. well above freezing) would have been absorbed by the fuel during refueling and would not have had time to settle at the bottom of the tanks before the flights took place.
As posted by Chriss Scott:
What’s so special about the B777-Trent? Does anyone find the hypothesis convincing?
Apart from the Trent being different from the other engines types, the plumbing in the airplane fuel system is no different then for the other engine types, except for the engine/fuel system plumbing interface.
No, i do not find the hypothesis convincing, especially when the weather conditions and actions taken to drain water while on the ground
for considerable times at Heathrow are taken into account.
Green-dot