Definition
In a helicopter autopilot system, the servo that automatically moves the antitorque pedals to control yaw and counteract the torque produced by the main rotor.
Plain English
An automatic device that pushes the helicopter's tail-rotor pedals for the pilot to keep the nose pointed where it should be.
Context Anchor
Seen in helicopter instrument flying and servo-failure discussions, especially when reviewing failures in automatic or assisted flight control systems.
Derivation
Anti' means against, 'torque' is the twisting force from the spinning main rotor, and 'servo' comes from Latin 'servus' (servant) — a small powered device that 'serves' by moving a control for you. Put together: a powered helper that works against rotor torque.
Why Pilots Care
Failure increases pedal effort dramatically and can lead to loss of directional control if not recognized and managed promptly.
Intuition Check
Do not read antitorque servo as a separate source of antitorque. It is not the tail rotor itself; it is the powered control device that helps move the antitorque system.
Example Sentence 1
When the antitorque servo failed, the pilot felt the pedals go light and immediately took manual control to hold heading.
Example Sentence 2
During the hover check, smooth operation of the antitorque servo allowed precise heading control with light pedal pressure.