Rapid lowering of the collective after touchdown may result in uncontrollable yaw to which direction?

Rapid lowering of the collective after touchdown may result in uncontrollable yaw to which direction?

• A. Right
• B. Left
• C. Front
• D. Rear

Answer: (A)

Yaw is controlled by the anti-torque system, provided by the tail rotor. When you rapidly lower the collective after touchdown, the main rotor’s torque demand drops quickly, and the tail rotor thrust decreases abruptly as well. That sudden loss of anti-torque thrust creates an unbalanced moment about the vertical axis. In the MH-65E configuration, this uncompensated torque tends to drive the aircraft’s nose to the right, producing an uncontrollable yaw to the right if not corrected with pedals. The other directions aren’t yaw directions, so they don’t describe this instability.

Yaw is controlled by the anti-torque system, provided by the tail rotor. When you rapidly lower the collective after touchdown, the main rotor’s torque demand drops quickly, and the tail rotor thrust decreases abruptly as well. That sudden loss of anti-torque thrust creates an unbalanced moment about the vertical axis. In the MH-65E configuration, this uncompensated torque tends to drive the aircraft’s nose to the right, producing an uncontrollable yaw to the right if not corrected with pedals. The other directions aren’t yaw directions, so they don’t describe this instability.