Submitted by Lou Kitz, Stoddard-Hamilton R&D
Although the Shur-Lok nuts make for a fairly easy installation, they have a cosmetic drawback. When installed from the inside of a composite skin, the shrinkage of the resin causes a slight dimpling inward of the outer skin. On our new Glasair models, this can be easily smoothed out prior to painting. For the gel-coated Glasairs, however, cosmetically filling and sanding with gelcoat is a lot more work. Here’s an alternative:
Make an attachment plate to match the base of the hardware or accessory, which is to be attached to the airframe. Relieve the inner skin layers and foam core back just enough to provide clearance for the nutplates. Place a two layer laminate over the area and pop rivet the plate in place. This procedure requires a little more work, but leaves the outer skin undisturbed.