I laid out and drilled #40 pilot holes for the 3/16” and ¼” bolts through the F-721B Aft Canopy Decks as shown on DWG 42, Detail A. I then drilled the aft pilot hole through both the upper surface of F-721B and the lower flange of F-721B.
The C-668 spacers were needed to provide a flat surface for the nuts and bolts that attach the roll bar to the longerons. See DWG 42, Section D-D.
I modified the C-668 spacers provided in the kit as shown on DWG 42, C-668 Detail Views.
When done, I had a forward left, forward right, aft left, and aft right spacer. The centerlines were marked on the upper surface of each spacer. I held the spacers, one at a time, in place against the bottom surface of F-721B and nested them tightly against the inboard edge of the longeron with the fastener centerline mark visible through the #40 pilot holes I drilled earlier. I drilled #40 through the pilot holes just enough (about 3/32” deep) to make a good center point for finish drilling the holes through the spacers off of the fuselage. I then removed the spacers and used a drill press to drill the #40 holes all the way through the spacers. Then I finish-drilled the holes to final size. I was careful to put the correct size hole in the correct spacer! #12 for the forward two spacers, ¼” for the aft two spacers.
I placed the Wd-641 Roll Bar on the fuselage in the position shown on DWG 42, View C-C.
The roll bar needed to have a 7/32” gap between the fuselage sides and the outer edges of the bar. If the gap had been within 1/16” of desired, I could have pushed or pulled it into position, otherwise I would have had to bend it slightly to make it fit within 1/16”. It could be adjusted quite easily by hooking one end behind something and pulling (to make it wider) or by putting one end on the floor and leaning on the other (to make it narrower). I went very slowly, as it was easy to do too much.
Once I had the width close, I clamped the roll bar in the proper position of the fuselage (vise grips worked well) and using a #40 bit, I back-drilled the 4 bolt holes up from the bottom using the pre-drilled pilot holes in F-721B as guides. The aft two holes were back-drilled using the holes in the F-721B flanges as well as the holes through the upper surfaces.
Time: 8 hours.
Leonard's RV-7A Build 