After several weeks of travel and preparation for a board meeting, I'm back in the shop. In the meantime I spoke with Caleb at ZAC regarding my elongated rivet hole in the bottom spar cap/doubler in the area of 20mm pitch rivets. He assured me that I could replace it with a 1/4 bolt (AN4-10). Today I was able to complete all the 6-14 rivets without any problem. I then reamed out the hole for the AN4-10 bolt that is shown on the plans on the inboard end of the bottom spar cap/doubler, and torqued the bolt in place. Next I step drilled the elongated hole using at least five intermediate bits, resulting in a very clean and straight 1/4 hole. I then placed and torqued the replacement bolt. Finally, I transitioned to the 5-9 & 5-10 rivets and successfully completed the bottom row.
