Assembly of Conical Fin to the Bomb Body
Prepare, inspect, and install a conical fin as follows (fig. 13-7):
1. Inspect fin for damage.
2. Ensure excess paint is removed from fin flange.
3. Ensure access cover is secure.
4. For a conical fin, retract all fin mounting setserews until screws are flush with the inside of the fin flange (all setscrews must be installed).
5. For a BSU-33 fin, ensure the clamp bolt on the band is retracted.
6. Ensure index pin in fin flange is not damaged.
7. Attach the arming wire to the aft lug (fig. 13-8). Thread the free end of Mk 3 arming wire from aft bomb lug through MAU-182 swivel ring and arming wire hole in top of fin.
8. Align fin behind bomb body with fin in the X-configuration.
9. Align pop-out pin with arming wire hole in top of fin.
10. Thread arming wire through the hole in top of the fin, and then through the fuze pop-out pin (fig. 13-6) and through the hole in bottom of fin (Mk 376).
11. Remove safety pin from pop-out pin (Mk 376).
12. Thread arming wire through two Fahnstock clips, gagrod, (fig. 13-6) and through the bottom of the fin (FMU-139/B).
13. Thread arming wire through two Fahnstock clips and the bottom of the fin, vertically align arming wire with arming wire slots located on gagrod arming wire housing (FMU-139A/B, B/B).
14. Push arming wire into arming wire housing.
15. Remove safety pin from gagrod.
Assembly of BSU-86 and BSU-85 Fins to GP Bombs
Inspect the BSU-86 fin (fig. 13-9) as follows:
1. Inspect fin for damage and improperly installed or missing parts and corrosion.
2. Ensure that the restraining band is free of corrosion. If damage is found or suspected, complete steps 3 through 7; if no damage, proceed to step 8.
3. Remove cotter pin from fin latch; ensure latch opens freely.
NOTE: If fins extend automatically at least 1/2 inch when the cotter pin is removed, and can be extended to contact the shock absorber by hand, the fin is operative.
4. Check that link pins and link pin retainers are present, not damaged, and properly positioned in the drag links.
5. Close fins and clamp together with vise grip pliers.
6. Relatch the release band, and insert warning tag assembly.
7. Remove vise grip pliers.
Figure 13-7.-BSU-33 series and MAU-93/B conical fins.
Figure 13-8.-Conical and BSU-33 series fin installation.
Figure 13-9.-BSU-86 bomb fin. 13-9
Figure 13-10.-BSU-85/B air-inflatable, retardable fin. 13-10
8. Ensure band, retainer, and release assembly are not damaged.
9. Ensure the lanyard swivel is installed on stowage.
10. Ensure the release lanyard and housing and the safety clip are not damaged.
11. Ensure the slotted spring (roll pin) is installed and is properly seated and not protruding from the clevis.
Inspect the BSU-85/B fin (fig. 13-10) as follows:
1. Ensure safing pin assembly, safety latch pin, and lanyard clip are properly installed
2. Ensure all setscrews are installed and flush with inside surface of the forward ring.
3. Viewing the retarder from the open attachment end, check that the rubber boots are secure and not damaged (fig. 13-10).
4. Open the pressure vent cap, ensure the nose fuze lanyard assembly is not damaged, and that the lanyard swivel assembly is attached to the stowage spring clip (fig. 13-10).
5. Ensure the safety latch is installed over the aft cover tang, the release latch pivot pin is not damaged, and the cotter pin is installed (fig. 13-10).
6. Ensure access cover is installed.
Installation of BSU-86 and BSU-85/B Fins
Install the BSU-86 and BSU-85/B fin assemblies to GP bombs as follows:
1. Attach arming wire to aft lug (fig. 13-11). Thread free end of Mk 3 arming wire from aft bomb lug through MAU-182 swivel ring and arming wire hole in top of fin.
2. Align fin behind bomb body with fin in the X-configuration.
3. Align pop-out pin or gagrod housing with arming wire holes in top of fin.
4. Align index pin with hole in bomb body, and press fin against bomb body.
5. Tighten all setscrews into groove in bomb.
6. On the BSU-85/B, remove access cover, and inspect arming wire. Alternately pull wire from top and bottom of retarder.
Figure 13-11.-Mk 3 arming wire and swivel loop installation. 13-11
Figure 13-12.-Arming wire and split clip installation.
7. Attach the split clip to the arming wire swivel, route the arming wire through the bottom arming wire hole, and then route forward (fig. 13-12).
8. Fabricate composite arming wire after it is routed through bottom arming wire hole in fin.
9. Attach swivel end of the composite arming wire to the split clip on the fuze lanyard assembly.
10. Tape the arming wire to the bomb body.
11. (BSU-85/B) Re-install access cover.
12. (BSU-86/B) Ensure the lanyard clip and safety latch pin are installed and the safety pin assembly is removed.
13. (BSU-86) Install fin release safety clip into retaining band latch.
14. On the BSU-86, remove fin safing pin assembly.
15. Wrap uncut Mk 3 arming wire around the fin, and feed excess wire into appropriate hole in fin.
If you want more information about the configuration and assembly procedures for the GP bombs, you should refer to Aircraft General Purpose Bombs, Fire Bombs, Practice Bombs, Fuzes, and Associated Components, NAVAIR 11-5A-17, and Airborne Weapons Assembly Manual, NAVAIR
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