TM  1-1520-240-10 2-5-2            2-5-2.  THRUST CONT Lever. Either THRUST CONT lever  712   (fig. 2-5-1) or  714A (fig. 2-5-1) is used to apply equal pitch simultaneously to both rotors, thus controlling ascent and descent of the helicopter. Raising the THRUST CONT lever increases pitch.  Lowering  the  THRUST  CONT  lever  decreases pitch. An integrated lower control actuator (ILCA) is installed between the THRUST CONT lever and the mixing unit. This actuator assists the pilot in moving the THRUST CONT Lever. A cockpit control driver actuator (CCDA) is also installed in the thrust control system. This actuator responds  to  signals  from  the  AFCS  and  increases  or decreases collective pitch on the blades to maintain a constant altitude. In addition, a balance spring is installed that   counteracts   the   downward   imbalance   of   the THRUST CONT level. NOTE If the THRUST CONT lever CCDA fails, the THRUST CONT lever will slip when force be- tween 7 and 23 pounds is applied. A BRAKE TRIGGER switch under each THRUST CONT grip controls the magnetic brake of the CCDA in the flight control closet. Pressing the switch applies electrical pow- er to release the magnetic brake in the THRUST CONT lever CCDA. The THRUST CONT lever can then be free- ly moved. When  barometric  or  radar  altitude  hold  has  been  se- lected, pressing the trigger will disengage altitude hold. When the switch is released, power is applied through the simplex clutch to the THRUST CONT lever CCDA and the AFCS will hold the altitude. Power is supplied to operate the THRUST CONT lever magnetic brake from DC essential bus through the THRUST BRAKE circuit breaker on the No. 1 PDP. The  712   THRUST CONT lever is also electrically linked to the power turbine actuator through the droop elimina- tor system. An upward movement of the THRUST CONT lever electrically increases the power turbine governor speed setting to compensate for inherent engine droop and maintain engine speed as rotor loads are increased. A  downward  movement  of  the  THRUST  CONT  lever electrically decreases the power turbine governor speed setting. The   714A    system  includes  both  thrust  lever  position compensation and thrust lever rate compensation. A detent capsule establishes a ground operation detent to reduce droop stop pounding. A viscous damper in the thrust control system improves control feel. Mounted on each THRUST CONT lever is an auxiliary switch bracket containing a SEARCH LIGHT control switch, a SLT-FIL (search light filament) switch, two ENGINE BEEP TRIM switches, and a HUD control switch. 2-5-3.  CYCLIC Stick. Each cyclic stick (fig. 2-5-2) is used for lateral and longitu- dinal control of the helicopter. Moving the cyclic stick to the right tilts both rotors disks equally to the right and causes the helicopter to roll to the right in flight. Moving the cyclic stick to the left causes the opposite movement. When moving the cyclic stick forward, the pitch of the fwd rotor blades is decreased collectively, while the pitch of the aft rotor blades is increased collectively, thus causing a nose-down helicopter attitude in flight. Moving the cy- clic stick aft causes the opposite movement resulting in a nose-up attitude. Two ILCA’s, one for lateral control and one for longitudi- nal control, are installed to assist the pilot in moving the cyclic stick. In addition to these actuators, viscous damp- ers are installed. One damper is for longitudinal control and one for lateral control to improve control feel. Located on the pilot and copilot cyclic stick grips are a CENTERING   DEVICE   RELEASE   switch,   an   AFCS TRIM switch, a CARGO HOOK RELEASE switch, inter- phonetransmitter TRIGGER switch, and a FLARE DISP (dispenser) control switch. 2-5-4.  CENTERING DEVICE RELEASE Switch. The CENTERING DEVICE RELEASE switch (fig. 2-5-2) is used to simultaneously release the force feel trim mag- netic brakes for the lateral, longitudinal, and directional flight controls. In addition, it disengages bank angle hold, heading hold, and heading select functions when AFCS is operating. Power is supplied to operate the magnetic brakes from the DC switched battery bus through the CONT CENTER circuit breaker on the No. 1 PDP. A centering spring and magnetic brake for each control provide a sense of force feel to hold the control in a trim position. However, the pilot can override the force manu- ally while maneuvering the helicopter. When the switch is pressed, electrical power is applied to release the mag- netic brakes. Each centering spring assumes a new trim position where the control forces are nulled. Releasing the  switch  removes  electrical  power  and  applies  the magnetic brakes. The centering springs are retained in their new positions.