Pressure/leak test left fuel tank

The left fuel tank was pressure/leaks tested to 0.1 bar initially, and later 0.07 bar (1 psi) using the manometer rig developed previously. The pressure was backed off a bit as the swelling of the tank was noticeable at the higher level, less so at 1 psi. Gas leak spray was used on all seams and rivets - no sign of leaks anywhere. No trend was evident with the manometer, only fluctuation by about 50mm attributable to temperature changes. The ambient barometric pressure did not change much over the test period, lasting 3.5 hours. In fact the manometer returned to the same level after 3.5hours as at the start of the test.

I then immersed the tank in water and examined for bubbles. None were found.

I could make this more rigorous, but it is evident there are no leaks of any practical significance.