TAIL ROTOR CONTROLS SYSTEM – GENERAL
The tail rotor controls system includes the yaw control. The yaw control is
obtained by changing the pitch angle of the tail rotor (TR) blades.
YAW CONTROL – MAIN COMPONENTS
PILOT PEDAL ASSY
The pilot pedal assembly is mounted on an articulated support that allows to
fit the physical characteristics of the pilot.
The pilot pedal assembly is connected to the copilot pedal assembly to give
a common input to the TR servo actuator.
The yaw pedal incorporates a microswitch used to operate the trim actuator
friction in order to disengage the anchor point.
COPILOT PEDAL ASSY
The copilot pedal assembly is mounted on an articulated support that allows
to fit the physical characteristics of the copilot.
The yaw pedal incorporates a microswitch used to operate the trim actuator
friction in order to disengage the anchor point.
YAW TRIM ACTUATOR
The yaw trim actuator is intalled in parallel with the yaw pedals, below LH
forward cockpit floor The Trim actuator has full travel authority on the yaw
control line.
The yaw trim actuator receives electrical commands from the AFCS and
converts these commands into a mechanical output used to change the
position of the yaw control linkage.
The Trim actuator incorporates:
• the Trim motor
• a magnetic clutch (Force Trim)
• an artificial feel device
• a dual position sensor (see chapter 22-00 for detail)
YAW DUAL LINEAR ACTUATOR
The yaw dual linear actuator is installed in series with the rods of the
mechanical linkage inside the tail boom to provide limited control inputs
commanded by the autopilot.
It is connected with the linkage through a dual-action bellcrank and an
anchor spring which provides a safety function in case the actuator
disconnects: in this case the spring reacts to the manual input as a pivot
point to ensure the movement is transferred to the tail rotor servo actuator.
YAW CONTROL – PRINCIPLE OF OPERATION
The tail rotor control is operated by means of a mechanical linkage that
gives an input to the dual-channel tail rotor hydraulic servo actuator. The TR
servo actuator acts the pitch-change mechanism to give the required yaw
action.
The mechanical linkage is operated by pilot and copilot pedals.
The mechanical linkage is also controlled by a yaw trim actuator and a yaw
dual linear atuator, both controlled by the AFCS (see chapter 22-00).