I had a hanger 9 SU 31 loose a wing in the pattern getting ready to land.On inspecting the remains I found that the spar webs pulled out of the grooves in the upper and lower spar caps.The reason they pulled out was that there was very little glue in the groove.It would of been impossible to inspect this area before it was assembled.To be simply put this stuff can only be inspected during assembly at the factory.Very poor qaulity on a very large airplane that has the capability of killing someone.It hit the dirt less than 50 ft from me and my truck.
I also had to put fiberglass reinforcements on the engine box,it was falling apart at all the seams.