Removed the area designated in Figure 1 page 25iS/U-02 with hatch marks from the lower ends of the F-1237C-L & -R and deburred the edges. Separated the F-1237BD into the F-1237B and F-1237D per figure 2 same page, filed and deburred. Separated the F-01437 into individual parts per figure 3 and filed and deburred. Removed the hinge pin from AN257-P2 hinge and fabricated the F-1237F from the two AN257-P2 hinge halves using the dimensions in figure 1 page 25iS/U-03. Drilled #30 one locating hole in each half of the F-1237F per dimensions in same figure. Drew line on the 12 1/2 half of the F-1237F per figure 1. Machine coutersunk one side of the F-01437A for AN426AD3 rivets per figure 2 same page. Separated the F-01437A into 4 individual parts per same figure. Cleco'ed the locating hole in the 13 1/2 half of the F-1237F to the F-01437, then aligned the parts and clamped them per figure 3. Match drilled #30 the holes in the F-01437 into the F-1237F. Cleco'ed each hole after drilling. Cleco'ed two F-01437A to the F-01437, then machine countersunk the F-01437 for double flush rivets. Marked the F-1237F and the F-01437A for reassembly then disassmebled, deburred reassembled and riveted per figure 3 page 25iS/U-03 creating the Seat Back Brace Assemblies.
Cleco'ed the located hole in the 12 1/2 half of the F-1237F to the F-1237A per figure 1 page 25iS/U-04. Centered the line drawn on the F-1237F with the holes of the F-1237A and clamped together. Match drilled #30 the holes in the F-1237A into the F-1237F and cleco'ed each hole after drilling. Marked the parts for reassembly, disassembled and deburred, then cleco'ed back together and riveted using LP4-3 rivets.
