Day 10:
The Pitot Tube Mounting Bracket Kit by Gretz Aero, LLC contains the following large items along with a bag of nut plates, screws, and rivets:
Draw a line around the interior perimeter of the backing plate that is 5/16 inch from each edge. Mark and then drill four holes on each of the three sides using a #40 drill bit. The holes should be 5/16 inch from the edge and 1 and 1/8 inch apart.
Draw a line 5/16 inch from the end of the backing plate on the side with the joggle. Hold the plate to the bottom of the rear spar and center the line in the holes from the spar.
Match drill it to the spar. Make sure to leave some distance between the edge of the mounting bracket and the rib.
Mark and then drill 4 holes in the angle that are 5/16 inch from the edge and 1 and 1/8 inch apart.
Cleco the skin and the backing plate in place. Match drill the backing plate to the skin. Then place carpet tape on the angle and attach it to the backing plate and the rib.
Match drill the angle to the rib and backing plate.
Disassemble and deburr the holes.
Ensure that the metal mast fits into the washer plate and backing plate. The parts can be cleaned up with a rotary file.
Trace an outline of the mast on the back of the wing skin. Make three holes inside the outline with a #19 drill bit.
Enlarge holes with a unibit.
Finish cleaning the cut-out with a rotary file.
Check for fit.
Instead of dimpling the skin and the backing plate, I countersunk the skin for a 1097 (small) head rivet.
The four screw holes get stepped up with a #19 drill for the #8 screws and then dimpled.
Use a hand squeezer to install the nut plates on the mast.
Installation is finalized when the skin is riveted to the wing.
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