There are six holes in the Rear Spar Reinforcement Fork that need to have #30 holes match-drilled into the Wing Rib flanges. These six holes are circled in the picture below.
Additionally, all common attach holes were final-drilled #30.....including all holes that will attach the Main Wing Ribs to the Rear Spar.
The holes in the Upper Flange of the Rear Spar that correspond to the three Rear Spar Doubler Plates needed to be countersunk to fit a Skin that has been dimpled for AN426AD3 rivet. I used my homemade guage to determine the proper depth of the countersink. The 16 hole locations are shown below:
The six holes in the Rear Spar Doubler (Inboard)......
.....six holes in the Rear Spar Doubler (Outboard).....
.....and the four holes in the last Rear Spar Doubler.
The next step is to countersink the two rows of holes on the W-1007C Rear Spar Doubler Plates. The bottom row had to be countersunk to accept the head of an AN426AD4 rivet. The top row had to be countersunk to accept a dimpled 0.020 Skin. Since I didn’t have a similar dimpled skin laying around, I looked forward in the plans to see what part would go here. Turns out, the W-00010-L (Left Wing) Flap Gap Fairing gets attached to this hole location. So, I decided to dimple the corresponding six holes in the Fairing and use the actual dimpled Skin as a depth guage. Worked out great. Once I had the depth set on the countersink cage/cutter, I used the same depth on the opposite Rear Spar Doubler for the same holes.
Now for the dreaded instruction that states......
Disassemble all parts. Deburr the holes and edges of all parts
Now that that’s all done.....
I dimpled all the non-countersunk holes in the flanges of Rear Spar (Left Wing for now). Here is a small example.....
Well, that is as far as I can go on the Left Rear Spar until it gets some Alumiprep and Alodine. The Rear Spar is to big to “dunk” and I will need to use a spray bottle and grey Scotch-Brite outside.....a little cold and dark right now!
In the meantime, I treated the Rear Spar Reinforcement Fork and Rear Spar Doubler plate with Alumiprep and Alondine.
Hanging up to dry.....
Tomorrow, I will prepare the Rear Spar and Akzo prime all three pieces. Once they dry, I can start riveting the Rear Spar assembly.