Laid out the 3 arm mount hole locations on inboard rib and drilled to 1/8" Laid out centerline on balance arm, marked 1st hole 8mm from end and drilled to 1/8" Placed inboard/outboard ribs back-to-back. Holding top flanges flush and offsetting outboard rib front flange about 1mm from inboard rib flange (to compensate for the 87 degree rib angle) then match drilled the arm mount holes in the outboard rib. Clecoed rear hole in inboard rib to arm, set 97 degree angle on arm and drilled other 2 holes in arm Using drill press I drilled the 3 holes through the opposite side of the arm With inboard rib clecod to arm I used drill press to open up all holes to 3/16". Did same with outboard rib To accurately locate the arm thru-hole in the front aileron web I marked lines on the rib flange parallel to the top and bottom surface of ther arm. Measured the distance from these lines to the center rivet hole then transferred these dimentsions to the aileron using the mating rivet hole in the web. After creating the opening using a step drill, snips and file I placed the ribs, slid arm through opening, bolted arm to ribs and clecod the inboard arm to the skin With the position set I match drilled the outboard rib to the holes previously drilled in the skin Balance arm assembly complete
