Initial Prep (Debur, Trim, Drill, and Cut) 3/9/24 – 1.3h 3/12/24 – 1.2h 3/13/24 – 0.9h This step starts with two pieces that are split apart to make a total of four parts. I separated the parts for this step when I separated parts in the first step of this section. The band saw made quick work of separating all of the parts for this section. Fine-tuning the parts with files and grinder wheels, followed by deburring, yielded nicely finished parts. [Hole and Edge Deburring Tools, Band Saw, Flat File, Bench Grinder with 6” Scotch Brite Cut and Polish Wheel, Dremel with Metal Cutting Disk] Final Prep (Dimple, Countersink, and Shape) 3/14/24 – 0.3h 3/23/24 – 0.3h Most of the final prep was countersinking holes in the top and bottom flanges of the Forward Center Section Bulkhead. The #40 holes in the top flange are countersunk for rivets to attach nut plates. The #30 and #40 holes in the bottom flange are countersunk to accept dimples in the bottom fuselage skin. There are also three holes in each bearing bracket brace to countersink prior to attaching the bearing bracket angles. [#30 Countersink Cutter, #40 Countersink Cutter; Microstop Countersink Cage] Prime 3/14/24 – 0.4h 3/23/24 – 0.1h [Grey Scotchbrite Pads, Bon-Ami Cleanser, Dupli-Color Degreaser, Rust-Oleum Automotive Self Etching Primer (Green – Rattle Can)] Assemble 3/23/24 – 0.2h 3/25/24 – 1.1h 4/15/24 – 0.6h 4/19/24 – 0.6h 4/20/24 – 2.8h The two bearing brace assemblies are each made by riveting a bearing bracket angle to the end of a bearing bracket brace. The bearing brace assemblies are installed between the two inboard cover ribs on each side of the airplane, and provide a rigid structure for the bearing brackets attached to the cover ribs. I installed the nutplates to the top flange of the Forward Center Section Bulkhead at the same time as I did the Aft Center Section Bulkhead. I was in nutplate mode, and this was an efficient way to quickly complete both. I hung the spar from the edge of the workbench, clamped it securely in place, and used the pneumatic squeezer with flat sets to set the rivets for the nutplates. Attaching the side angles to the forward bulkhead was similar to the process used on the aft bulkhead. The side angles have one bolt installed at this time near the top of the bulkhead, and rivets in the top and bottom most holes help keep things aligned. Clecos do the rest to hold everything together during riveting. Like before, I used the C-Frame for the universal head rivets with excellent results. The final assembly step was attaching the cover ribs and bearing brace assemblies to the Forward Center Section Bulkhead. I started by inserting bolts in the top and bottom holes of the cover ribs, and then ensured the ribs were aligned using rivets in the remaining top and bottom holes prior to tightening the nuts to the final torque. The easiest setup for me to install the bolts and rivets was to lay the bulkhead across two saw horses with the cover ribs hanging down. I set all of the rivets on the cover ribs with the pneumatic squeezer, but had to use varying yoke sizes to get clean looks at each rivet through the bulkhead lightening holes. After the cover ribs are completely installed, this step is finished with the attachment of the bearing brace assemblies to the cover ribs and bulkhead. I started by attaching the bearing brace assemblies to the cover rib with the bearing bracket by installing two structural screws with washers and nuts in each. I used the torque wrench set to 25 in-lbs to torque the nuts on the screw. There are 2 rivets opposite the screws that get set next. The pneumatic squeezer did a nice job with these, but clearance on the rivet closest to the bulkhead is very tight. I set the final three rivets in each assembly to the bulkhead with a rivet gun and bucking bar. One note on the final three rivets - they are longer than the rivets used to attach to cover ribs to the bulkhead. The rivet size is specified in the drawing, but it is easy to overlook. I figured it out after using the shorter rivet and noticing that the shop head was not formed correctly. I drilled out the short rivet, and continued with the longer rivets - all good! [Pneumatic Squeezer, 1” Yoke, 2 1/2" Longeron Yoke, 3” Yoke, Flat Squeezer Set, Torque Wrench, C-Frame, Cupped Set, 3x Rivet Gun, Long Cupped Rivet Set, Tungsten Bucking Bar]