In article , Larry Dighera wrote:
On Sun, 5 Dec 2004 07:40:00 -0600, "Dan Luke"
Which is an old wives tale. The amount of water contained in 20-30
gallons of air is insignificant.

A Piper PA28-235 can have 84 gallons of fuel in 4 tanks, so leaving
them half empty, for instance in a humid maritime environment,
overnight where the temperature drops sufficiently to cause the
moisture to condense out of the 40 gallons of air contained in them,
will result in enough water in the fuel system to interfere with
operation of the aircraft's power plant.

I have lived my entire life in humid maritime environments. I have never
lived more than 50 miles from open sal****er despite having lived on two
continents. Where I currently live, it is impossible to be more than 7.5
miles from open water.

However, I have never discovered water condensing in half-full fuel
tanks. It is my practise to make both a visual inspection through the
the filler neck and to sump the tanks before flying whether the plane's
been refuelled or not. In over 1000 hours of light plane flying, the
only time I've found water in the fuel is through leaky fuel caps (the
Beech Musketeer being the worst for this, but also in a Grumman Cheetah)
after a night of rain.

So I'd agree the condensation thing is an OWT, certainly with the fuel
capacities of our planes (the biggest capacity wise that I've regularly
flown are an S-35 Bonanza (74 gal usable) and the Geronimo-mod Apache
(which carried 7 hours of fuel - I don't remember the exact figure in
gallons, but it was a little over 100 gallons capacity in 4 tanks).
With the Geronimo, because it only has 160 hp a side, it's quite
important not to lug around excess fuel.

--
Dylan Smith, Castletown, Isle of Man
Flying: http://www.dylansmith.net
Frontier Elite Universe: http://www.alioth.net
"Maintain thine airspeed, lest the ground come up and smite thee"