11. Turned the aileron upside down, and drilled the bottom skin to the tip rib, from the trailing edge to the front, all while holding the flange tangent to the skin edges.
12. Turned the aileron right side up and drilled the top skin, again holding the flange tangent to the skin edges.
13. Drilled #40 and clecoed the top skin to the 20-mm flange.
14. Inspected the assembly carefully and decided that the construction was satisfactory. Adjusted the clecos to every other hole.
