"Angus Davis" wrote in message ...
Yossarian wrote:

I understand that functional fuel gauges are required equipment for day VFR
flight.

Per the FARs, your gauges were functional. The only requirement is that
when the tanks are empty, the gauges read empty.

Sorry, the FARs don't say that. The FARs don't say anything about accuracy.
The much misattributed FAR about them being empty just says that the E mark
means zero usable.

If they show full when
the tanks are 1/4 full, that is not a problem in so far as the FARs are
concerned.

91.205 says you must have operational guages. In this case the guage is NOT operating
the way it was designed. If the thing is really bouncing between 0 and Full on the ground
there is something seriously wrong. Not only is it hardly legal, I'd really question what
was going on.

Repeating, the only regulatory requirement is for gauges to
be accurate when the tanks are empty.

Repeating, you are wrong.

That's why you should pay little
attention to them at all, and do your fuel calculations with diligence.

Yeah and I have had two close friends who have put airplanes into off airport landings
because they decided not to look at the gauges. You should take the pessimistic
approach of always believing the gauges if they tell you that there is less fuel than
you predict by your preflight planning, but not if they tell you that there is more!