From the top of my head (A330-200/A340 classic):
FQI at high quantities:
+/- 0.5% of total capacity (approx. 110t) plus +/-0.5% of actual FOB
narrowing down to no overread a low quantities and -1% (?)
fuel flow transmitters:
Don^t have figures at hand, but was told that they have max. accuracy at cruise fuel flow, and are really bad at ground idle and max. thrust.
A few years ago, the Trent 500s on the A3456 had quite an issue when the flight crews complained a lot about discrepancies, like:
- 100t t/o fuel
- 90t Fuel used
- 15 (or 5t) fuel remaining
From an engineering point, the comparison is a bit like apples and peaches...
But from a flight deck perspective, certainly understandable...
Tried to dig out the ATA 73 TFU at home - but didn^t succeed...
The issue then got solved by recalibrated / new FF transmitters. If I recall correctly.
Best Regards, J. V.