Brief Description: Drill-Countersink-Dimple for Fuel Tank Nut Plates
This operation took a lot of time. Some of the gotchas were not so obvious. Watch your clearances for riveting #40 nut plate holes. There is metalwork behind that spar flange you need to take into accout when you are positioning the nut plates. Not necessary for the row on each side that takes the standard K1000-08 nut plates. They go right on. The lower (aft) row use the K1100-08 countersunk nutplates and you need to either dimple the spar flange or countersink the spar flange depending on whats behind each hole. The inboard-rmost K1100-08 nut plate had to have a little of the side ground off to fit properly next to a spar doubler inside. Normally to drill the mounting holes for the nutplates, you hold them in place with the 1/8 inch clecoes through the middle holes. Those holes were still #30s. Afterwards you drill those out to #19. I thought I enlarged all of those but you can see in photo 2 I missed one. So in that case, you install a screw backwards into the nutplate all the way so it will stick out the front end of the nut plate and you can place that screw through the #19 hole and then drill your #40 mounting holes. You can see the spar flange dimpled on a completed K1100-08 nutplate. That particular nutplate was angled to avoid skin riveting issues later.
K1000-08 go on forward row of holes
K1100-08 go on aft row of holes. Special Fix here
Corner K1100-08 installed with dimpled spar flange
