Originally Posted by Barkingmad #1
Subsequent checks showed the ramp minus totaliser readings had crossed over to above the tank total line, which eventually managed to recover some of its "lost" fuel as more was consumed.
Originally Posted by Skyjob #6
Scavenge Pump Inlet located most aft of tank, this should (over time) be drawing all remaining center fuel out, but this takes time, and sometimes this pump is not effective enough to drain the tank remains before landing, then resulting in an apparent fuel quantity in the center tank which is yet to be used.
Doesn't that explain it? When the center pumps switch off, the fuel remaining in the center tank is temporarily 'unavailable'. It is available again after the scavenge pump has transferred it to the wing tank.