"Roger" wrote:
Which is an old wives tale. The amount of water contained in 20-30
gallons of air is insignificant.

Just let those tanks inhale and exhale a few times. They do that
every morning and night so there is a *lot* more than 20-30 gallons
involved.

Another OWT, I'm afraid. Can you produce calculations to show how many
air exchanges/week occur in a half-full 40-gal. tank given a daily
temperature swing of 20 deg. F?

[snip]

I fly a Deb with about the same fuel capacity (not counting the tip
tanks). With half tanks and the plane hangered for two weeks in the
Spring, I drained over two full samplers of water out of one tank and
a half out of the other. None out of the auxiliaries as they were
full.

Since you bring up anecdotal evidence, I'll chip in: I've been parking
my airplane under a shelter within a mile of Mobile Bay for five years.
I never top up the tanks after a flight. In that time, I don't recall
ever sumping a drop of water out of any of the drains. My tanks hold 32
gal. usable each.

[snip]
--
Dan
C172RG at BFM