48 holes in the flap brace to drill. First thing was drilling the flap hinge to the wing skin. I set the flap a snug as I could, trying to eliminate some of the mismatch of the trailing edge compared to the aileron trailing edge. After the hinge and skin were drilled, I removed the flap and hinge and clamped the flap brace underneath the wing skin and match drilled the brace through the holes I made drilling the hinge to the skin. The other edge of the flap brace has #30 holes to match drill to the rear spar when I finish fitting the brace properly. I reinstalled the hinged flap back on to see the total fit of all pieces. I need to shave off more of the rear skin so the hinge will open the flap closer to 90 degrees. Right now the hinge pinches and stops at about 60 degrees and its hard to get your hand through the opening on top to install/remove the two-part flap hinge pin. Marked where to file, removed the flap, and filed the wing skin/flap brace edge about 1/16 to 3/32. All edge distances were still within riveting tolerances. Finally, I dimpled the wing skin and set up the flap brace to countersink.
Flap brace match drilled to wing skin.
Inboard view showing fit and #30 holes for rear spar riveting
Outboard flap brace fit and step up onto rear spar doubler.
