Assemble 6/9/2021 – 1.7 hours Attaching the aft bottom skin to the aft fuselage assembly sounds easier than it is. I started by riveting the #12 bulkhead to the aft bottom skin, which has a very small radius rolled section at the end of the part. The rolled area is where the bulkhead and skin attach, and the small radius and tight quarters rules out back-riveting or using a pneumatic squeezer to set the 8 rivets. I was left with using the rivet gun and a narrow tungsten bucking bar (BB-07) to set the rivets. I also had to get a little creative on how to clamp the part to the work bench to provide an accessible and stable riveting area. Riveting on the small radius also presented some challenges to setting the rivets flush with the skin. The final results were pretty good, but it took a lot of thought and experimentation to get there. [3X Rivet Gun, Swivel-Head Flat (Mushroom) Set, Tungsten Bucking Bar, Clamps] 6/11/2021 – 3.7 hours The aft bottom skin assembly with the attached #12 bulkhead is installed between the bottom and side skins and the bulkheads and J-Stiffeners. You have to remove most of the clecos aft of the #10 bulkhead to get enough clearance to insert the aft bottom skin. It is still a very tight fit – especially where the aft bottom skin is inserted between the #10 bulkhead and the bottom skin. The order of the layered parts from the inside of the aircraft out is the F-01410 (#10) bulkhead, the F-01479 aft bottom skin, the F-01478 bottom skin, and finally the F-01473—L and -R side skins. Once the aft-bottom skin is clecod into position, the skin is riveted to the #11 and #10 bulkheads starting from the center and working toward the edges. Access to the ##11 rivets with the bucking bar is very tight, and I spent a long time devising a riveting strategy. My solution was to use the special bucking bar from the elevator assembly to reach into the small cavity between the #11 and #12 bulkheads. I was very pleasantly surprised by the results with the long bucking bar, which I also used on the forward side of the #11 bulkhead and the #10 bulkhead. I had to go to a shorter tungsten bucking bar in the radiused area of the skin at the #11 rib, for the 4 sets of the two outer-most rivets. I did that by reaching through the open access panel at the back of the fuselage. Each rivet took a long time to set up and finally drive, but the extra time resulted in good rivets with no drill-outs or dings in the skin. [3X Rivet Gun, Swivel-Head Flat (Mushroom) Set, Tungsten Bucking Bar, Special RV-14 Elevator Bucking Bar]