Initial Prep (Debur, Dimple, and Countersink)
8/10/2021 – 0.4 hours
8/14/2021 – 0.6 hours
8/15/2021 – 1.3 hours
8/17/2021 – 0.6 hours
There aren't many empennage parts left on the shelf. I started the deburring process for this step with the upper aft fuselage rib. The rib has long continuous edges and a relatively small number of holes, so deburring this part is pretty quick. There is also a J-Stiffener that attaches to the top skin, but that part was deburred and primed several steps ago. The final piece to debur was the top skin. There are several holes, but only four long and straight edges with no facets.

Dimpling the Skin Doubler, Upper Aft Fuselage Rib, and J-Stiffener required several different dimpling techniques. I started with the 22” C-Frame and reduced diameter dimple dies for the holes next to the flanges of the skin doubler, since those holes are too close to the flanges for the larger diameter dies. I then switched to the larger diameter dies for the remaining #40 holes in the skin doubler, and switched again for the #30 holes in the doubler. I dimpled the flange of the upper rib and the J-stiffener with the pneumatic squeezer and reduced diameter 3/32” dimple die. There isn't enough clearance for the flange to lie flat for the C-Frame, but the squeezer fit the area quite well.
[Hole and Edge Deburring Tools,22” C-Frame with #40 Reduced Diameter, #30, and #40 Standard Diameter Dimple Dies, Pneumatic Squeezer with #40 Reduced Diameter Dimple Die]

Final Prep (Trim, Cut, Shape, and Drill)
08/15/2021 – 0.2 hours
The first step on this sheet is to put a slight break in the side and aft edges of the top skin. I have had problems with this operation in the past, but this time it went very well. The break is straight along the edge, and I feel like it is close to the right amount. Previous attempts typically had too much of a break, which resulted in sloppy breaks or skins that didn't lie down completely flat. I struggled with that concept thinking the more exaggerated the break, the tighter it will fit; but a fellow builder pointed out that too much break might actually lead to skins that don't fit tightly between the rivets. We'll see how this one turns out, but I feel good about it at this point.
[Edge Forming Tool (Vise Grip Style)]

Prime
07/24/2021 – 0.5 hours
08/14/2021 – 0.3 hours
08/17/2021 – 0.3 hours
08/18/2021 – 0.5 hours
Priming all of the pieces for this sheet followed my now-standard process of scrubbing and scuffing the parts with cleanser and a Scotchbrite pad followed by a thorough cleaning rinse. I go back to the final preparation items like dimpling after the part is cleaned, and then degrease the parts just prior to priming.
[Grey Scotchbrite Pads, Bon-Ami Cleanser, Dupli-Color Degreaser, Dupli-Color Self-Etching Automotive Primer (Green – Rattle Can)]

Assemble
08/24/2021 – 0.3 hours
08/26/2021 – 0.7 hours
Back-riveting was a good choice to attach the doubler, rib, and stiffener to the top skin. I have access to a large 6' x 9” back-rivet plate, which was very handy for this step. I started by back-riveting the edge rivets on the skin doubler. Access to those rivets would have been much more difficult with the rib in place. After setting the edge rivets, I placed the rib into the assembly and riveted the rib and the rest of the doubler to the skin. I started in the middle of the rib and worked toward the ends by setting the center rivets in each section and continuing that pattern until all the rib rivets were set. I then placed the J-Stiffener in place, and used the same center out technique for that part. I was very happy with the final result, and I'm looking forward to using the assembly to close-out the aft fuselage soon.
[3x Rivet Gun, Back-Rivet Set, Large Back-Rivet Plate]