Helicopter Flight Controls Overview

Helicopter Flight Controls

• Helicopters are controlled by three flight control systems: Cyclic, Collective Pitch, and Tail Rotor
• The Cyclic Control System manipulates main rotor attitude by changing blade pitch
• Cyclic Control System components include:
  • Push-pull tubes
  • Torque tubes
  • Bellcranks
  • Boost cylinders
  • Swashplate
• The Collective Pitch Control System adjusts the pitch of all main rotor blades simultaneously
• The Collective Pitch Control System components include:
  • Push-pull tubes
  • Torque tubes
  • Bellcranks
• Tail Rotor System provides directional (yaw) control and compensates for engine torque
• Tail Rotor system components include:
  • Pedals
  • Cables
  • Pitch change mechanism
  • Tail rotor blades
• Rigging is a critical step after installation or replacement of control system components
• Rigging involves ensuring proper alignment and adjustment of system components to achieve desired response

Rigging Collective Pitch System on Model 47G-4

• Key tolerances are 1º for angles and 0.06 inches for dimensions
• Low pitch blade angles should be checked before flight
• Level the helicopter and ensure the main rotor mast is vertically aligned
• Position the pitch stick at 37.5º above horizontal and adjust the low pitch stop
• Bottom the cylinder piston and adjust the rod length
• Adjust the collective lever screw to maintain a 1.075 inch dimension and low sleeve position
• Adjust the link rod to achieve a 2.97 inch dimension and low pitch positioning
• With the system in low pitch, push down on the cylinder piston, adjust the tube assembly to fit and shorten the rod by 1/2 turn
• Move the collective pitch sleeve boot up on the mast
• Mark the mast at the end of the collective pitch sleeve and 0.84 inch above for high pitch positioning
• Move the collective stick to the high pitch position and adjust the high pitch stop
• Adjust rigging aid screws to ensure gaps of 0.20 inches with collective stick at both low and high pitch positions