Tail Rotor Actuator

The TRA is double effect tandem actuator, with two separate hydraulic sections acting on the same
piston, connected to the two independent hydraulic systems of the helicopter. The actuator can
operate also with only a single hydraulic supply active.
The TRA is designed to have two different inputs to command the output rod position:
– a manual pilot input, connected directly to the pilot sticks
– an electrical command managed by the fight computer.
The electrical command is the input of the Stabilization Control Augmentation System (SCAS), whose
function is to provide superimposed control at the pilot input command to stabilize the helicopter
against outside disturbances, and augmenting or helping pilot control input.
The SCAS has a limited authority.