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Wendell Voto wrote:
I find it interesting that you get water in the sump on a Velocity. A previous owner of one told me that since the tanks are composite/sandwich structure that water does not condense in the tanks and never got any moisture in the fuel. Where are you getting fuel? Could it have water in it? (they put water in everything now days to "enhance it" or make you pay $4 a pound for it).
Wendell
Please, everyone, please understand that ANY closed tank with a small orifice opening (a vented fuel tank, for example) can become a very effective water pump. The process:
-You spend Saturday flying, and park the plane on the ramp in anticipation of Sunday's flight. The hot sun keeps the fuel in the half full tank warm for the rest of the evening.
-As the sun sets, your tanks begin to cool. Cool gasses occupy less volume, tank sucks air in through the vent (exactly as it was designed to do). Unfortunately, it's sucking air at exactly the same time as water is dropping out of the air mixture. This may be more of a problem in North Carolina than other locals, but evenings here can be downright sticky in the summer. The air that the tank is sucking will be VERY wet.
-When the tank warms in the morning, the gases will expand and it will push out the air above the fluid. The water that was in the air is now below the fuel, so it doesn't get pushed out.
-You can't make it to the airport Sunday, so the plane sits on the ramp all week. Each day, the tank will heat and cool, sucking in a gulp of wet air every night.
The end result is a pumping action. A very insidious and unavoidable one. It doesn't matter what they tank is made of. A full day's heat soak, followed by a full night's cooling will make the pump work. The only way to stop is to:
1)Live in a place without water vapor problems. Either a very dry environment, or one so cold that all the water sits frozen on the ground.
2)Seal the tank perfectly completely. At which point it won't work well as a vehicular fuel tank, but at least won't have to worry about water in the fuel.
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