Which device receives pressure from the backup pump for actuation of the 2nd stage tail rotor servo?

• A. 2nd stage tail rotor servo
• B. Tail rotor gearbox
• C. Engine oil pump
• D. Flight control computer

Answer: (A)

Hydraulic power from the backup pump is used to drive tail rotor control through actuators. The component that actually uses that pressure to move the tail rotor pitch is the second stage tail rotor servo. In a dual-hydraulic setup, the second stage servo converts the incoming hydraulic pressure into the mechanical motion that adjusts the tail rotor blades. The tail rotor gearbox simply transmits the motion once the servo positions it; it isn’t the device that receives the backup-pump pressure to actuate itself. The engine oil pump provides lubrication, not hydraulic actuation for the tail rotor, and the flight control computer sends electrical commands to servos rather than delivering hydraulic pressure. So the backup pump pressure specifically actuates the second stage tail rotor servo.