Kieran and I completed the drilling and mounting of hinges for left flap (left aileron done already). Flap wanted to bow out slightly (1/8”) in the middle, away from the the rear wing spar. This was evidenced by the centre flap hinge having to be pulled toward the rear spar when it was pinned. Sighting down it we could not tell if the cause was a bow in the flap, the rear spar bowed in the other direction, or a difference in the dimensions of the hinge points, which stand about 3”aft of the rear spar or a combination of factors (most likely). In any case, the flap needed to be flexed inward toward the rear spar slightly (1/8”�in order to connect the hinge. We decided to take out half of the discrepancy by placing one large washer under each of the three mounting points of the centre flap hinge bracket where they bolt onto the rear spar. In this way, we averaged out any error (we think). The flap now only has to be flexed half as much (now 1/16”). Everything looks straight, and the flap and aileron are SMOOTH with plenty of range-of-motion. One wing to go. Biplane guys must have a lot of patience. Tomorrow we will roll the wing over and install the pushrods, flap springs and and control cables to the point where they exit the wing. Then coil the excess and leave it inside the wing until wing mounting.