Brief Description: Drilled and installed first tube frame
1. Located gussets 6B21-4 and 6B21-8. 2. Located shoulder harness fitting 6B21-3. 3. Marked hole locations per dwg 6B21. 4. Drilled #40 pilot holes. 5. Protected center line marking on 6B21-1 with transparent tape. 6. Marked 1" increments from either end of 6B21-1 to facilitate equal removal of material from each end. 7. Removed first 1" from end of rube on band saw. 8. Checked installed length, and repeated step 7, until part nearly fit. 9. Filed end of material for controur matching in installed position. 10. Clamped in place, and back drilled through pilot holes in gusset. 12. Removed tube and gusset 6B21-3 for cleanup. 13. Clamped gusset to seat back gusset 6B15-1, and back drilled with #30 drilled. 14. Deburred gussets, and primed mating surfaces with zinc chromate primer. 15. Riveted 6B21-3 and 6B15-1 with A4 rivets. 16. Re-clecoed to forward tube 6B21-1, and re-clecoed to airframe.
