I haven't been following the thread but have just been forwarded this:
OFTEN WHEN TRYING TO DETERMINE WHY SOMETHING WENT WRONG . . . . I try to see what Civil Air Regulations said about it. In this case it is CAR 4b - section 435(b) . . . I was trying to figure out why the fuel filter iced-up on the BA 777 Glider at Heathrow. I found it. this subparagraph said . . . . [(d) Provision shall be made to maintain automatically the fuel flow when ice-clogging of the filter occurs, unless means are incorporated in the fuel system to prevent the accumulation of ice particles on the filter.]
This Standard missed the transition from CAR 4b to FAR Part 25 or Part 33 - Engines. The B-777 has a fuel heater but it merely requires a certain temperature. Too bad we didn't stay with the automatic Bypass feature!
JIM