The trainer that I just got done repeatedly killing went through Nylon wing bolts like candy. I had to order a 100 Ct. bag of them from the Airplane factory because when I first started flying it I would sometimes cart-wheel on either takeoff or landing. Also in every single crash the nylon bolt would shear, especially in ones where the wingtip impacted first. Bear in mind that the wing was mounted to the square alluminum fuse by two tandem bolts, one metal 1/4" right behind the wing spar and one nylon 1/4" right before the trailing edge. They do shear on my trainer, but I dont think that they will on my cub, which has four bolt/dowel insert points.