Servo-Control System

The servo control system uses hydraulic pressure from the hydraulic system to boost the main rotor controls, assisting the operator in moving those controls. It consists of the components that follow:

• Left servo-actuator

• Left servo-actuator support

• Collective servo-actuator

• Collective servo-actuator support

• Right servo-actuator

• Right servo-actuator support

The three servo-actuators and their supports are the same. A servo-actuator is an assembly made from aluminum, steel, and corrosion resistant steel parts. It consists of the cylinder, piston, valve, and rod end. The rod end has the trunnion, pin, pin pivot, and link. It is mounted at the end of the piston shaft. The valve is mounted on the piston shaft and is connected to the link. The piston slides in the cylinder with its two shafts extending from the cylinder ends. Two conduits inside the piston shaft exit inside the cylinder and apply the hydraulic pressure to either side of the piston. The end of the cylinder, near the valve, has two pins to mount it to the servo-actuator support. The servo-actuator support is made from cast aluminum and has two bushings made from corrosion resistant steel with teflon liners. The bushings are the pivot for the pins of the cylinder.

Left servo-actuator

The left servo-actuator boosts the left up-and-down motion of the cyclic, changes it to a fore-and-aft motion, and transmits it to the left boosted link.

Left servo-actuator support

The left servo-actuator support holds the left servo-actuator and the left actuator support bellcrank. It is located at the forward end of the truss assembly, on the left side, and over the cabin roof.

Collective servo-actuator

The collective servo-actuator boosts the up-and-down motion of the collective, changes it to a fore-and-aft motion, and transmits it to the collective boosted link. It is an assembly made from aluminum, steel, and corrosion resistant steel parts. It is mounted on the collective servo-actuator support.

Collective servo-actuator support

The collective servo-actuator support holds the collective servo-actuator and the collective actuator support bellcrank. It is located at the forward end of the truss assembly, in the center, and over the cabin roof.

Right servo-actuator

The right servo-actuator boosts the right up-and-down motion of the cyclic, changes it to a fore-and-aft motion, and transmits it to the right boosted link. It is mounted on the right servo-actuator support.

Right servo-actuator support

The right servo-actuator support holds the right servo-actuator and the right actuator support bellcrank. It is located at the forward end of the truss assembly, on the right side, and over the cabin roof.

Operation

The operation is given for one servo-actuator. The operation for the three servo-actuators is the same.

The actuator support bellcrank moves the servo-actuator trunnion forward and aft. This motion is transmitted to the link by the valve input arm pivoting on the rod end. The link controls the valve, which applies the hydraulic pressure to the piston to move it in the correct direction. The boosted motion is transmitted to the boosted link by the rod end.