Scott, I must have missed the part about this glider not being certified. Obviously if it's an experimental, none of Part 43 applies, including the Appendix A stuff about major repairs, and the Appendix B stuff about Form 337s. My bad.

Indeed, AC43.13-1B can now be used as approved data for small unpressurized airplanes provided it doesn't conflict with manufacturer's data. It didn't used to be that way, but Bill O'Brien was instrumental in making this change before he retired from the FAA and shortly thereafter passed away. Bill was a wonderful friend to aviation maintenance, and is sorely missed.