Brief Description: Cockpit rails and seat back support
I called a local RV-8 builder this morning and asked him to drop by and give me an opinion regarding the fit of the cockpit rails. The rails don't fit as advertised at the two center section bulkheads. This seems to be a common problem as reported in various forums. There are varying opinions as to the best solution, most saying just get the outboard edges as close to flush with the side skins as possible and match drill. While that solution is fine structurally, I don't like the way it looks.
I am thinking about positioning the rails so they are flush and then match drilling them to the upper flanges on the center section bulkheads. This will undoubtedly result in elongated holes in the flanges (the prepunched holes won't align perfectly). To correct for the elongated holes, I have made doubler plates to be match drilled beneath the flanges giving the rivets a clean plate for the shop heads (may use -4 rivets as well). I think this will make a nice job and still be structurally sound. I just want to get the opinion of another RV-8 builder and an A&P certificate holder.
I also test fitted the back seat support weldment and noted the problem with edge clearance on the aft most number 8 screw that goes through the rail into the weldment. Thankfully, I found this problem described in some other websites before following the shop instructions. With some very careful positioning, clamping, and drilling, I think the edge clearance issue can be resolved. I plan to start with a #40 and then a #30 from underneath before deciding upon whether to final drill to #19 from the top. If the edge distance is too close I may substitute a rivet for the screw.
