Image 1 shows the first time I've encountered a bad mis-match between the pre-punched kit parts. All of the rivet holes lined up just fine but the eventual hole for the flap motor drive pushrod missed by about 1/2 of the diameter of the pilot holes. SInce they couldn't both be right and I liked the edge distance on the Drive Bracket I decided to treat it as the master tool. Image 2 shows me match drilling the pilot hole in the Drive Bracket with the inboard Flap Rib and Image 3 shows me opening up the hole to the final size of 1/4 inch. If you look carefully at image three I am using my new 3/8" pneumatic drill that I decided to get for drilling the larger holes. I've already noticed that it uses a lot more air than the 1/4" drill.
Pre-Punched Hole Mis-Match
Drilling Pilot Hole Using Flap Drive Bracket as Guide
Opening Hole in Flap Drie Bracket and Inboard Rib to Final Size
