Aug 23, 2022     Fuel Tanks - (12 hours)       Category: Wings

Over the past few weeks have found and fixed a few leaks on the back channels of both tanks. After latest fixes, have done two types of testing on the tanks. The first was water testing using distilled water where tanks were filled approximately 1/3 of the way. Tanks were turned on both sides to ensure all seams/rivets held and also elevated both ends of the tanks to check end ribs. After confirming this, then took out of the jig and laid on rubber mats on top of table in the configuration the tank would be on the wing (ie fuel cap up and angled towards root end). Tank was then filled with more water to approximately 1/2 and checked - still no leaks. Also checked that both fuel senders were functioning properly with different water levels.

After confirming water tests, then did water column test with 1psi pressurization using a tube to the vent line (703mm of water in tube). At first I thought there may be a leak as the water level varied slightly throughout the day, but it was going both up and down. Upon some research, it appears this can be normal with weather/temperature changes. I will watch for another 24 hours and as long as it stays within this small range, will conclude they are leak free.

I preferred the water method as it was easier to find leaks but the pressure test is helpful as it will be needed to confirm the tank after it has been attached with cleco's to the wing. Once pressure is confirmed when mounted on the wing, then will do final riveting to the wing.