Originally Posted by
etudiant
I don't know why that would not get picked up by the instrumentation, should there not be a large fuel flow discrepancy?
Fuel flow is measured going into the engine. Hard to say from the video if the engines are running. Not enough spillage to show up on the quantity indicators. Not a 767 person but as said above, either a failed check valve in the dump system or the plane was topped off while cold and as the day's temperature climbed and the hydraulic pumps were turned on preflight the surge tank filled and vented outboard.