Regardless of how you think of it the wing will experience relative
pressures in the range of 1 psi in service so that is probably a reasonable
pressure at which to test.  5 psi may not be reasonable.

Gary,

 

You had to be there to hear how much air and vaporized fuel came out the vent and how much the skin was distorted although I am sure it was nowhere near 5 psi.  In any event, the 320/360 wings are built upside down so the spars and ribs are well attached to the upper skin with 2 bid reinforcing such construction.  The wing bottom is merely glued on (in my case with the Lancair supplied 3M fuel proof bonding material, not Hysol) to the spars and flox filled/fitted 5/8" rib cross sections.  As I said, this was the pre cap strip technique and I would feel a lot better if I was always flying inverted.  Note that it is the top wing skin of the Legacy that is glued on and all the ribs are built with at least 1.25 inch flanges (cap strips)!

 

It's incredible that the whole thing stays together since I seldom fly out of the yellow arc, even in turbulence.

 

Clean

Sand

Clean

Clean

Glue