Prepare the W919 Attach Strip

I drilled the screw holes out to #19 size after getting the nut-plates #40 holes drilled. Deburred all the holes then dimpled just the #19 with a #8 die for the screws. I was still undecided on the method of installed the AD426 rivet... either Dimple or Countersink the W919 strip. After doing some reading i'm going with the NAS1097 shear rivet which is actually the preferred method. Using these rivets i will just need to do some light countersinking of the W919 piece and nothing to the nut-plate! The reason i can do this is because the NAS1097 rivet has a much lower profile head and the W919 is thick enough to allow a relatively small countersink.
Test material, notice the smaller head on the bottom left rivet. The Shank diameter of both of these rivets are the same.

From Pete and Tad's RV-9a Build

From Pete and Tad's RV-9a Build