1. Mark the centerline of each flange of each rib and rib assembly.
2. Position 4 flap ribs with flange pointing inboard, and one flap drive rib assembly, flange points outboard in each flap skin. Align centerline of ribs in center of holes in skin. Drill to #40 and cleco in position.
3. Detail for the flap drive rib on left flap. Flange points outboard.
4. Trim and bend flanges of flap skin as necessary to obtain a tight fit. The tighter the fit, the better the aileron will look. A loose fit when riveted will cause the skin to bulge between the ribs.
