The front spar doubler sits on the forward side of the front spar, and has a variety of hole patterns. Today I clecoed and final drilled the holes, deburred, and then countersunk twelve holes on the face of the doubler. Then I countersunk the inner most 9 holes on both spar flanges. These will be under the vertical stabilizer and don’t have a skin covering. I messed up on one countersink on the flange, enlarging the hole slightly, probably a couple hundredths of an inch too deep. I’ll look at it again tomorrow, but I may just upsize to a -4 rivet.
Next I’ll be fluting and shaping ribs, and then I’ll prime all of the HS parts, hopefully this weekend.