We recently had an ASW27 come in to the shop with a bit of runway rash on the belly. It wasn't too bad but did need some attention. Along with fixing up the ding there was some previous damage to the forward section of the nose that needed to be cleaned up as well.
The damaged areas were sanded, cleaned and prepped for the repair. The repair was made with a hot bonder under vacuum. The function of the bonder is to control the rate at which heat is applied to the repair area so as to complete the cure of the epoxy resin. In this case the heat source was a silicone heating pad (orange pad in photo) that was placed over the top of the repair and under vacuum.
Vacuum is applied to evacuate off gases from curing of the resin so as to remove any resin voids and to compact the repair ply's. Vacuum is maintained throughout the curing and cool down cycles.
The results of the bonder/vacuum repair are excellent. With the fiberglass repair cured it is ready to take a close-up look at the repair. Through a lupe the repair is examined for resin content and voids.
The next step was to fill with an epoxy filler to restore the shape of the fuselage. This is a multiple step process of applying filler, sanding and repeating the process until the shape is reclaimed. Once the filler is completed the primer is sprayed on. One last pass with fine sandpaper then the repair is ready for paint. For this repair an acrylic urethane was used as that was what the sailplane was painted with.
The final results are as good as new!