In both cases, the helicopter will advance in the direction of stick movement. Movement of the stick laterally will move the helicopter right or left, corresponding with stick movement. This movement occurs by retracting and extending the left and right lateral primary servo cylinders. The collective pitch control system provides vertical control of the helicopter. Movement of the collective pitch control stick is sent through control rods and bell cranks to the appropriate auxiliary servo cylinder.
Movement is sent from the servo cylinder to the mixing unit.
At the mixing unit, all vertical movements of the collective sticks are sent to the primary servo cylinders and the rotary-wing swashplate. At this point, the pitch of all blades increases or decreases equally and simultaneously. A balancing spring attaches to the control rods to help balance the weight of the collective stick. A friction lock on the pilot s collective stick applies the desired amount of friction to the tube of the collective stick. The lock prevents creeping during flight.