If both tail rotor control cables fail, a centering spring will position the tail rotor servo linkage to provide __ of pitch.

If both tail rotor control cables fail, a centering spring will position the tail rotor servo linkage to provide __ of pitch.

• A. 5 degrees
• B. 10.5 degrees
• C. 15 degrees
• D. 0 degrees

Answer: (B)

When the tail rotor control cables are lost, the only mechanism left to move the tail rotor is the centering spring in the servo. This spring biases the servo linkage to a fixed, mid-range tail rotor pitch, providing a predictable amount of anti-torque thrust so the helicopter remains controllable. For the UH-60S, that default pitch is 10.5 degrees. This value is chosen to give enough tail rotor thrust to counter main rotor torque without causing over-rotation or instability. A smaller pitch would not counter torque adequately, a larger pitch could create excessive yaw forces, and zero pitch would mean no anti-torque thrust at all. Hence, the centering spring sets 10.5 degrees of pitch when control cables fail.

When the tail rotor control cables are lost, the only mechanism left to move the tail rotor is the centering spring in the servo. This spring biases the servo linkage to a fixed, mid-range tail rotor pitch, providing a predictable amount of anti-torque thrust so the helicopter remains controllable. For the UH-60S, that default pitch is 10.5 degrees. This value is chosen to give enough tail rotor thrust to counter main rotor torque without causing over-rotation or instability. A smaller pitch would not counter torque adequately, a larger pitch could create excessive yaw forces, and zero pitch would mean no anti-torque thrust at all. Hence, the centering spring sets 10.5 degrees of pitch when control cables fail.