Page 63.6 Chapter 63 Main Rotor Drive System APR 2017
63-20 Main Rotor Gearbox Assembly
A. Removal
1. Remove main rotor blades per § 62-10.
2. Remove tailcone cowling assembly per § 53-23.
3. Disconnect (pitot system) 15-4-N-O union near G201-1 (servo support) frame
assembly. Cap fitting and plug line.
4. Refer to Figure 63-1. Remove hardware securing F908-1 and F910-1 yoke
assemblies to plate assemblies, leaving plates attached to shaft weldments. Note
hardware removed.
5. Remove hardware securing F121-7 push-pull tube assembly to F339-1 jackshaft
weldment, and F121-5 push-pull tube assemblies to D212-5 servo assemblies.
6. Detach cable assembly from (rotor brake assembly) B112-3 spring.
7. Using back-up wrench, disconnect D205-19 and D205-20 hose assemblies from
F006-1 main rotor gearbox and D500-3 oil pump. Cap and plug fittings and hoses.
8. Disconnect F059-01 cabin harness assembly plug from F049-01 gearbox harness
assembly receptacle. Remove hardware securing A936-3 (ground) wire assembly
to F560-1 bulkhead assembly.
9. Remove D277-8 clamp or cut and discard safety wire securing Tygon® tube to
G254-1 (fuel) vent assembly, and clear tubing from workspace.
10. Install hoisting equipment per § 7-20, Part A, steps 1 thru 4; remove hoist slack.
11. Remove hardware securing F252-1 strut to F020-1 upper frame assembly. Remove
(mounting bolt) nuts and washers securing gearbox to upper frame. Remove aft
mounting bolts securing F235-13 strut assemblies to servo support frame, hardware
securing struts to upper frame, and struts.
12. Hoist gearbox (with hydraulic installation, servo support frame, and mast fairing
assembled) up and away from helicopter.
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