I'm not sure there is a task in the RV building process that makes the builder more nervous than drilling the aft spars...first flight maybe? So today I decided it was time to get it done and move on to the next big thing.
After leveling the fuselage and checking the sweep one more time, I used a 3" block and the level to check for the proper incidence. The manual says that the actual incidence is less important than having both wings the same, but I guess I feel better having both parameters met. This meant that I had to file a little bit off of the right spar to gain clearance from a rivet to raise the spar about 1/16", but once this was done both wings were the same and the incidence checked per the plans. Time to drill.
Again, the plans call for using a drill guide...which I had...but which proved useless. The reason was that there is absolutely no space to use the drill guide and still ensure that the drill bit is actually in the proper place. In the end I simply used a clamp as the guide. I figured that the clamp was perpendicular to the spar assembly so I just lined up on that and drilled.
After drilling a 1/8" pilot hole, I used sequentially larger drill bits and then a .311 reamer for the final hole. All's well that ends well...the aft spar holes are done.
