I'm a religious believer in checking sumps every pre-flight, and have occasionally found some pretty high amounts of water this way.
However, as I look at the workflow for pre-flighting my design, accessing the fuel drains at the bottom of the tank is going to be awkward. Basically, the tank is in the middle of a high-chord wing, so the low points (two of them) are more than four feet from the leading edge and trailing edge; and the clearance between the wing bottom and the ground is less than three feet, so accessing them would be a crawl-on-hands-and-knees affair.
One thing I thought of was to run "straw" lines down to the very bottom of the tanks at the low points, below the fuel pump pickup, run those to a more accessible location (keeping them above tank top level to avoid siphoning concerns), and put a normally-closed valve and a primer bulb on each, in a more convenient location. Workflow would be to hold open the valve with thumb and forefinger, squeeze bulb with rest of hand, and collect enough fuel from each line to exceed the volume of the line so that some of the sample is definitely coming from the sump. This is only a few ounces, and a graduated collector cup could make it easy to be sure.
If all samples are clear (including the gascolator one, which will probably be a conventional setup since it's easier to access), toss it back in the left tank as your counter-clockwise walkaround continues; if any have any sign of contamination, either keep pumping until all clear, or more likely get on your hands and knees and check the actual sump drains.
Thoughts? Alternate ideas? Other approaches to this problem?
However, as I look at the workflow for pre-flighting my design, accessing the fuel drains at the bottom of the tank is going to be awkward. Basically, the tank is in the middle of a high-chord wing, so the low points (two of them) are more than four feet from the leading edge and trailing edge; and the clearance between the wing bottom and the ground is less than three feet, so accessing them would be a crawl-on-hands-and-knees affair.
One thing I thought of was to run "straw" lines down to the very bottom of the tanks at the low points, below the fuel pump pickup, run those to a more accessible location (keeping them above tank top level to avoid siphoning concerns), and put a normally-closed valve and a primer bulb on each, in a more convenient location. Workflow would be to hold open the valve with thumb and forefinger, squeeze bulb with rest of hand, and collect enough fuel from each line to exceed the volume of the line so that some of the sample is definitely coming from the sump. This is only a few ounces, and a graduated collector cup could make it easy to be sure.
If all samples are clear (including the gascolator one, which will probably be a conventional setup since it's easier to access), toss it back in the left tank as your counter-clockwise walkaround continues; if any have any sign of contamination, either keep pumping until all clear, or more likely get on your hands and knees and check the actual sump drains.
Thoughts? Alternate ideas? Other approaches to this problem?
