First I put plugs in all of the fitting of the sump, except the drain, in which I put a bushing with a Schrader (thread - valve style of a tire), and the vent in which I put a barbed fitting. I then could put a tube with water in it on the bar and pump air in through the valve. I put enough pressure in the tank to cause the difference between the high side and the low side of the water level to be about 20"

A quick word about the pressure. I measure distance between the bottom of the fuselage and the top of the strake to get an idea of the fuel pressure head on the sump. It is about 20". Fuel is 6 lbs. per gallon and water is 8. From that I decided that a water column 3/4 the height would be the same pressure as fuel (15"). I was then able decide that 20-25" of water would be plenty.

The objective to make sure the sump was sealed and then use it as a barometer. That is easy because you can get all over it and even (retract sump here) put it in a tub and look for bubbles. I quickly found that all of the plugs leaked without some sealant. Once they were sealed, it was tight. Now I have a comparable test system.

7/16/2011   Picture 147