Malcolm Teas wrote:
]

Hm. An FAA certified fuel gauge has to be right on two conditions:
full and empty,
Actually, an FAA certified fuel guage doesn't have any accuracy
requirements at all.

The only thing that the regs say is that the empty mark is supposed
to correspond to no usuable fuel (rather than bone dry).

My "certified" gauge doesn't even read "full". The guage (it has
a disclaimer on it) gives "no indication above 36 gallons". (39.5
usable).