"John T" wrote in message ws.com...
"Gary Drescher" wrote in message
news:sxfKb.750122$Tr4.2074796@attbi_s03

against the watch... The watch rules!

Rather than letting either kind of measurement rule, I always assume
my fuel is the LESSER of the time-calculated amount and the
gauge-indicated amount.

Good point. One should consider the possibility of a fuel leak.

Or some problem with the carb, or the fact you forgot to lean, or whatever.
The accident reports are full of stories of people who went through fuel faster
than normal and "the fuel gauges were erratic, so I ignored them" (That was the
literal text from the crash report for a 172 now on sale on eBay...see another
thread).

We picked our plane up from annual one year. Margy had done the owner assist
along with the IA and another mechanic. They buttoned her up and I took the
non-IA A&P who was a student pilot at the time on the test flight. We flew around
for a few minutes, landed, and opened her up and saw no leaks or other signs of
abnormality.

The next morning Margy and I departed for Oshkosh. Margy was flying and
was busy trying to negotiate a class B clearance with Dulles. After about 15 mins
I notice the fuel gauge was now down to nearly a half tank. Now it's real easy
to misfuel a Navion (but it's not a mistake that I've made since shortly after I
bought the plane) and I point this out to Margy and I say I'll keep my eye
on it. Sure enough it's trending downward. We're halfway between two
airports and I can see Margy trying to decide. Leesburg I say and she informs
ATC (who had just given us our class B transition) we're diverting.

She lands and shuts down. I go off to hunt for a mechanic, by the time I return with
one, Margy has removed the lower cowling. (The mechanic asks how I get her
to do that, and I pointed out she had just finished doing the annual, I get to only
do the heavy stuff...pulling the prop etc...). Margy hops into the cockpit and
hits the boost pump and sure enough a stream of fuel emits from the engine driven
pump. The fitting is only finger tight, we apply a wrench to it and all is well.

I figure for the 20 minutes of flying, we were burning 60GPH. Fortunately we
were carrying 100 gallons at the time. As hot as it is in August in DC, the fuel
that had leaked had just pretty much vaporized by the time we shutdown and
opened her up.