Removed aileron brace to give access to end of wing. Mounted, clecoed, and drilled aileron hinge bracket to L wing. Countersunk one rivet hole for AN426 flush rivet (others are AN470 rivets.) It appeared initially that one of the factory-matched holes on the end rib was drilled incorrectly, causing the rib to push the aileron bracket slightly out of line with the chord line. I checked this later, and realized that the ribs have a lot of play in them. After riveting the aileron bracket, the rib lined up perfectly.