SECTION V. FLIGHT CONTROLS

TM 1-1520-240-10 2-5-1 SECTION V. FLIGHT CONTROLS 2-5-1. Flight Control System. The helicopter is controlled by changing the pitch of the blades either collectively or cyclically. Pitch changes are made by the pilot’s movement of the flight control which include a THRUST CONT (control) lever, a cyclic control stick, and directional pedals. The pilot’s controls are in- terconnected with the copilot’s controls. Flight control movements are transmitted through a sys- tem of bellcranks, push-pull tubes, and actuators to a mixing unit just aft of the cockpit, next to the forward transmission. The control movements are mixed to give the correct lateral cyclic and collective pitch motions to the rotors through dual hydraulic actuators. These dual boost actuators are under each swashplate. Each set of dual boost actuators is normally powered by both flight control hydraulic systems. The helicopter is vertically controlled with the THRUST CONT lever through application of equal pitch to all bla- des. Directional control is obtained with the directional pedals by imputting equal but opposite lateral cyclic pitch to the blades. Lateral control is obtained by application of equal lateral cyclic pitch to the blades with the cyclic control stick. The helicopter is controlled longitudinally with the cyclic stick through application of differential collective pitch. In addition, the helicopter has an advanced flight control system (AFCS). AFCS provides the following features: a. Rate damping in all axes and sideslip stability. b. Pitch and roll attitude hold and heading hold. c. Airspeed hold. d. Improved control response in pitch, roll, and yaw. e. Barometric and radar altitude hold. f. Automatic coupled turns. g. Longitudinal cyclic trim scheduling. THRUST CONTROL LEVER (ON HELICOPTER WITH THRUST CONTROL LEVER (ON HELICOPTER WITH 714A ENGINE 712 ENGINE 2 Figure 2-5-1. Thrust Control Lever