ShyT, one question. How often was the pump flow rate checked? Pump capacity can decrease over time. ?????
The pump (fuel vendor's) flow rate does not affect the accuracy of the measuring gauge so the indicated amount +/- the specified tolerance will be correct UNLESS the meter has gone wrong. If we're prepare to consider the possibility of failure in the a/c then we must investigate the fuel uplifts. First place to start is the last time the tanks were visually brimmed, which gives the last 100% reference.