On Feb 21, 8:36*pm, Ray Andraka wrote:
I didn't say that the gauge could be inoperative. *

Sorry, I didn't mean to suggest that you yourself were promulgating
the full-blown legend.

All I said was that there was nothing in the FAR that says it
must be calibrated to a certain tolerance. *

Yup, that's certainly true.

The only requirement for calibration is that it
indicate empty when there is no usable fuel left in the tank. *

But the tolerance for THAT isn't specified, either! Whether the fuel
quantity is zero or nonzero, the only requirement is for an
"indication" of that quantity. By common sense, the indication has to
be CORRECT, within some reasonable (but unspecified) tolerance.
There's nothing in the regs to suggest that the indication for an
empty tank has a more stringent accuracy requirement than the
indication for any other level has.

If the gauges are operative, indicate empty when on an empty tank, and increase
monotonically when fuel is added, I think the letter of the reg is met.

I disagree. I don't see why you substitute an implicit monotonicity
requirement for an implicit accuracy requirement. Surely it's fine to
have a gauge that is highly accurate, but has regions of negligible
nonmonotonicity; and surely it's not ok to have a gauge that's wildly
inaccurate (say, reporting 50 gallons when there are really just 5)
but monotonic without exception.