Fabricate the 4 C-668 spacers that are needed to provide a flat surface for the nuts and bolts that attach the Roll Bar to the longerons (DWG 42 Section D-D).Each spacer has a unique location and must be marked. Deburr spacers. Mark the center line on the upper surface of each spacer. Hold the spacers, one at a time, in place against the bottom surface of F-721B so that the center line mark is clearly visible through the #40 pilot holes drilled earlier. Drill #40 through the pilot holes about 3/32" deepin the spacers. Finish drilliong spacers using a drill press (#12 forward, 1/4" aft). Deburr, clean and prime spacers.
