29-30 Hydraulic Servos (continued)
B. Servo Installation (continued)
7. a. Forward Servo: Install hardware securing servo to F121-5 push-pull tube’s upper
rod end. Standard torque fastener per § 20-32 and torque stripe per Figure 5-1.
b. Aft Servo: Install hardware securing C343-8 tube’s lower rod end to F339-1
jackshaft weldment. Standard torque fastener per § 20-32 and torque stripe per
Figure 5-1. Using backup wrench, standard torque jam nuts and palnuts, and
torque stripe per Figure 5-1.
8. Refer to Figure 5-2. Verify proper rod end centering on all push-pull tubes attached to
servos.
9. Remove caps and plugs. Lubricate new packings using A257-15 hydraulic fluid and
install packings on servo unions and tees. Install fittings with associated hardware in
servo ports and connect D205 hose assemblies to fittings. Align fittings to minimize
hose preload and ensure hose clearance with surrounding structure; special torque
fittings per § 20-33 and torque stripe per Figure 5-1. Special torque hose B-nuts per
§ 20-33 and torque stripe per Figure 5-1.
10. Bleed hydraulic system per § 12-34.
11. Perform the following measurements on all servos just installed:
a. Measure and record dimension between clevis hole center & top of servo piston.
b. Apply cyclic and collective frictions. With collective full down and hydraulics
unpressurized, position cyclic stick so piston in servo just installed is in its lowest
position. Measure and record dimension between top of servo piston and top of
cylinder assembly.
CAUTION
Dimension between clevis hole center and top of servo piston
must be 1.40 ± 0.03 inches; dimension between top of servo
piston and top of cylinder assembly must be 0.28 ± 0.03 inch;
dimension between C343-8 tube’s rod ends must be 4.00 ±
0.03 inches. If dimension(s) recorded are not within required
range, adjust to correct dimensions in Part B steps 1 and 2,
proceed with servo installation thru step 10, then perform main
rotor rigging per § 18-40.
12. Install tailcone cowling per § 53-23. Install mast fairing per § 53-22.
Page 29.8 Chapter 29 Hydraulics MAY 2015
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