Are tandem rotor helicopters susceptible to Unanticipated Yaw?

• A. False
• B. True
• C. Cannot be determined
• D. Sometimes

Answer: (A)

Tandem-rotor aircraft balance yaw through opposite torques from the front and rear rotors, and yaw is produced only by a deliberate differential in collective pitch between the two rotors. Because the rotors’ torques oppose each other, small disturbances tend to be damped and there isn’t a persistent, uncommanded yaw tendency like you might see with a single-rotor helicopter fighting an unsupported tail rotor. In normal operation, unanticipated yaw is not a typical issue; commanded yaw is handled by adjusting the differential collective to generate the desired turning moment. Only a mechanical fault that disrupts rotor synchronization or torque balance would risk an unexpected yaw.