Returned to Section 26 to assemble seatbacks. Cut seatback angles as per Steps 1-3, page 26-02. Deburred all angles and primed F-1237C and F-1237D angles. Fabricated seatback hinges and seatback brace hinges as per Steps 4-9, page 26-02. Match-drilled seatback brace hinges as per Steps 10 and 11, page 26-02. Began match-drilling of seatback hinges as per Steps 12 and 13, page 26-02.