The negative force gradient spring cancels
feedback loads exerted by the rotary rudder during
It also cancels feedback loads when the
auxiliary hydraulic system is off. When the rotary
rudder is stationary, an initial force is required to
move either pedal from its extreme position. With the
auxiliary hydraulic system on, the effect of the
negative force gradient spring is zero.
The negative force gradient spring is
preloaded to 600 pounds. To prevent
injury to personnel or damage to flight
controls, carefully follow the maintenance
instructions provided in the MIM.
FLIGHT CONTROL SYSTEMS
The basic components of the helicopter flight
control systems are the auxiliary servo cylinder, the
mixing unit, the primary servo cylinders, and the
Auxiliary Servo Cylinder
This cylinder consists of four separate banks of
servomechanisms constructed as a unit. Figure 10-7
shows the fore-and-aft bank of the servo cylinder.
The other banks are similar in design and operation,
except as noted in the following paragraphs.
The hydraulic power pistons of each bank help
flight control movements before the movement is sent
to the mixing unit.
The cylinder operates on
mechanical input during manual operation of the
The cylinder operates on electrical
input from the ASE, and on electrical input from the
stick trim system.
Each of the four banks operates in a single area of
control functioning, providing fore-and-aft, lateral,
collective, and directional hydraulic aid. Each bank
has a mechanical and electrical input hydraulic servo
valve capable of displacing the pilot valve shuttle for
ASE operation. Additionally, the fore-and-aft and the
lateral banks have a pair of solenoid-operated stick
trim valves. These valves control fore, aft, and lateral
movements through the stick trim system.
Figure 10-7.Auxiliary servo cylinder.