"Dan Luke" writes:

How much water is there in 40 gallons of air, Larry? Assume that when
the airplane was parked, the temperature was 20 C and the air was
saturated (which would be extremely wet conditions, BTW).

An opportunity to disturb high school chemistry knowledge cobwebs!
Water has a 20mb vapour pressure at 20degC, so water would form 2% of
the sea level atmosphere at full saturation. The ideal gas law
indicates there would be about 0.12mol in there, which has a mass of
around 2.2g, which could condense to around 2mL. Not much, but if it
decides to freeze and get sucked in and collected, could it plug up a
fuel line?

- FChE