Originally Posted by Leodis737
And the timing fits. Scavenge from centre tank to wing tanks starts when 29,000 pounds of fuel (total) remaining - i.e. roughly within half an hour of landing on the grass at LHR. (see post 572).
No.
Originally Posted by B777 Flight Manual
With the main tank pumps ON, a scavenge system operates automatically to transfer any remaining center tank fuel to the main tanks. Fuel transfer begins when either main tank quantity is less than 29,000 pounds.
(my emphasis.)
So not 29,000 total, but 29,000 in either wing tank. Wing tank capacity is 64,100 pounds, each.
Bernd