rocketbob
Well Known Member
This theory doesn't explain blisters under vinyl wrap.
Might be changes in formulation of the ProSeal though.
I've been saying for years its the in-fuselage loop in the vent lines that causes paint blisters. Slug of fuel in the loop puts enough pressure in the tanks to cause outgassing via imperfections in the sealant around rivets.
Many certified aircraft that are non-strutted have a vent line that extends to the tips via a Dukes flapper check valve with a small hole drilled in the body of the valve. This does two things: 1. allows for venting even when parked on a sloped surface and 2. Drains the vent line back into the tank to prevent the slug of fuel from increasing pressure in the tank.
I've never seen blisters on wet-wing airplanes, other than RVs.