"Peter Duniho" wrote in message ...
"Malcolm Teas" wrote in message
om...
Hm. An FAA certified fuel gauge has to be right on two conditions:
full and empty. No assurances of correctness anywhere else.

Illegal cell phones, and now this old wives tale?

It's retread week!

I dunno about that. I'm repeating what I learned from an instructor
of mine who's also an A&P. At your kind suggestion above I tried
to track it down on the FAA website.

TSO-C55 is titled "FUEL AND OIL QUANTITY INSTRUMENTS (RECIPROCATING
ENGINE AIRCRAFT)", so that looked good. But it just refers me to SAE
Aeronautical Standard AS-405B, "Fuel and Oil Quantity Instruments,"
dated July 15, 1958 for the details. It refers to older standards as
well.

Aeronautical standards are downloadable for $59 each from the SAE site
www.sae.org.

AS-405B was updated in July 2001 to AS-405C and now handles both
float-type and capacitive instruments. (Capacative instruments were
also covered in an earlier standard from 1989.)

Also there's TSO-C47 from 1997 that covers "PRESSURE INSTRUMENTS -
FUEL, OIL, AND HYDRAULIC". Unfortunately it also deadends into a SAE
document. There's nothing in either TSO that answers this question.

I'd expect that at least some of the difference of opinion we're
finding are from older vs newer standards. Like we say in the
computer biz, the nice thing about standards is that there's so many
of them to choose from. Anyone got a extra $59 or so and want to
resolve this? I'm curious, but not $59 curious.

In any case, regardless of the standard, we all know about planes with
fuel gauges that are at best a hint to your fuel condition. Seems
best to track time as well as gauges like someone suggested.

-Malcolm Teas