I teach from a large fleet of Piper archers, arrows, and seminoles. We
never leave full tanks overnight, always "to the tabs", or "40 a side" in
the PA44. I've NEVER pulled water from the sumps UNLESS it rained (piper
caps leak, period). Even after a HEAVY dew, the only drops of water i've
sumped were the drops i saw drip in when i was visually checking the fuel
level (and yes i waited for them to sump out!). Have to agree that
condensation into fuel would contribute only mildly to water contamination.
Now then, fueling out away from home airport i've gotten "wet" fuel before,
but even that wasn't more then a pea sized bubble of water in the bottom of
the jar. Worst case i've ever seen was a particularly bad rainstorm in FL,
used a GATTS jar, it became a 50/50 mix of water/fuel, looked rather
spectacular. Kind of makes you wonder how much water gets into the system
when flying in a heavy rainstorm.....

That said... i NEVER even consider starting the engines unless i check fuel,
even if all i'm doing is taxiin the aircraft form one place to another,
don't want to pull a slug of water, contaminates, whatever INTO the fuel
lines for the next guy to get stuck with in the air (tho in THEORY it will
settle out into the gascolator/engine sump.)

"RST Engineering" wrote in message
.. .
(a) You can go through the math all day long and still not explain why I
have drained the (hangared) 182 after a particularly humid day or two and
get a tablespoon or two of water in the quick drains.

(b) You cannot explain why "drain the sumps" is a daily check list event
for both fuel trucks AND airplanes.

(c) You cannot explain why CessBeePipMoo all have drains at the low point
of the fueling system. It would be a hell of a lot cheaper not to have to
put them in there. Somebody somewhere thought it was a good idea.

(d) You cannot explain why a hangared 150 from this airport fifteen years
ago dumped it into a pasture off the end of the runway and then proceeded
to drain two QUARTS (yes, that's quarts) of water from the tanks.

Jim


"Dan Luke" wrote in message
...

"RST Engineering" wrote:

I would ten times over risk gas theft over water condensation overnight
in half-full or nearly empty tanks.

There's not enough water in 20 gallons of air to matter.

How much water is there? In *extremely* wet conditions (saturated air at
20 deg. C) there are only 14.7 g/kg of water in the air. A cubic foot of
air at SLP weighs about 34 grams at 20 C. 10 gallons is ~27 cu. ft., so
that gives about 900 g. of air and about 14 g. of water. Not a problem.

--
Dan
C172RG at BFM