I think the problem is also the brand of the hinge material. I used to use the Radio South hinges 10-15 yrs ago on my pattern airplanes and never had a problem. The "newer" hinges from GP, H9 etc are different in that they seem to just be the white "material", whereas the old Radio South hinges were heavy plastic that were bonded to the white CA "material" on both sides. I had 2 H9 CA hinges fail on my .40 size trainer that I use for radio testing. I have a GP Pitts and a Wagstaff, and both use this "cheaper" CA hinge material. I threw out this stuff and used Robart hinge points. FWIW