This morning was tedious, but necessary for the ER tanks. I drilled some #21 holes for the future #8 screws, but now I needed to drill some nutplate attach holes around those #21 holes, then countersink them for future installation of nutplates. (Future like next weekend, not distant).

I took a single picture today of my nutplate holes (screw hole center, nutplate attach holes surrounding) showing how I was able to position it to “capture” the original leading edge skin hole. It looks bad now, but the screw hole countersink will eat this up and it’ll be good as new.

I had done some the last few days, but this is basically 30 holes top and bottom for two spars. 120 holes, 2 nutplate and countersunk holes for each #21 hole.

240 countersinks. Ugh.

2.5 hours. I’m booking this against the ER Tanks, even though it was spar work.

My remaining list for the wings (aiming for top skin riveting in two weeks):

1. Install spar nutplates.
2. Drill skins to final size.
3. Disassemble all.
4. Deburr and dimple skins.
5. Debur and Dimple ribs, rear spar
6. Rivet ribs to spars.
7. Temp Install ER and Std Tanks (requires drilling and dimpling the attach holes of the tank skins).
8. Top Main Skin Riveting
9. Build ER and Std Tanks