Brief Description: Main Spar Nutplates and Tiedown Bars
Today I primed the holes and attached the nutplates on the top flange of the right spar and both flanges of the left spar. I also primed the holes and attached the #4 center section nutplates on the forward side of both spars. I was able to work out a process where I was able to rivet all 30 #8 fuel tank attach nutplates on one flange in 20 minutes.
I also got the W-731 tiedown bars and the W-426 spacers ready for fitting to the spars. I used a 1" hole saw to drill the lightening holes in the spacers before I cut them out of the bar stock. Due to their small size, deburring the 1-inch holes was a pain, but I finally got it with needle files and 100-grit sandpaper.
The tiedown bars are supplied at 7-1/2 inches long, but the drawing calls for 7-15/32. A quick trip to the belt sander took care of that extra 1/32". The drawing calls for drilling 3/16" hole in the top outboard corner of the bar flanges so you can bolt the bar to the spar and backdrill the other 7 holes. I drilled that hole and can't get an AN3 bolt through it, nor the holes in the spar for that matter. Checking the AN3 bolt specs, they can be as large as 0.189 in diameter, whereas 3/16 = 0.1875. I think I'll check on sources for a #12 or #11 reamer.
Rivets today: 208 Rivets Total: 2517
I used the spar bags as masking before priming.
Shot and bucked center section attach nutplates. Also pimed inboard z-bracket nutplates.
Drilled spacers and initial attach hole in tiedown bars.