Dan Luke wrote:

"RST Engineering" wrote:


(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.


I see: math is false and your charming story is proof. Very convincing.
I have one too: I've been keeping a 172RG with 62-gal. capacity tanks
outdoors in one of the most humid places in the U. S. for six years. I
never top the tanks unless I specifically need to for the next flight.
Only once in that time have I ever had water in a sample, and that was
due to a bad fuel cap gasket.

So, you've got your little story and I've got mine--so what? I'm the
one with the real numbers on his side.

My 182 was parked outside most of its life and we have fairly humid
summers here in upstate NY. I never found water in the fuel in 6 years
of owning the airplane. We used autogas and me and my partner both
tankered gas to the airplane and filled if before leaving, not after
returning. My partner had water problems before installing the flush
style gas caps, but none after that unless he pumped the water in while
fueling up. :-) I had a filter on my tank that also trapped water, but
he didn't and put some water in one time.

I think most water that gets to the drains comes in either through a
leaky gas cap or was pumped in with the gas. I don't think condensation
is a big issue. If it was, it would likely affect you more in flight
than on the ground as you climb up into cold air with humid warm air in
the tanks.


(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.


You cannot explain why your anecdotes conflict with empirical knowledge
of the composition and behavior of the atmosphere. Come back when you
can.

Yes, I can't explain that for sure, but I'll bet it was from a leaky gas
cap, not from condensation. It would take years to suck enough air
through the vents and condense out the water to get two quarts.
However, with a leaky gas cap, this could happen in one or two
thunderstorms.


Matt