What is the recovery procedure from retreating blade stall?

What is the recovery procedure from retreating blade stall?

• A. Reduce collective pitch; Regain control of aircraft
• B. Increase collective pitch to regain speed
• C. Apply full left pedal and hold
• D. Push forward cyclic to increase airspeed

Answer: (A)

Retreating blade stall happens when the blade on the retreating side of the rotor reaches a high angle of attack at low forward speed, causing a sudden loss of lift and a tendency to yaw and roll toward the retreating side. The quickest way to recover is to reduce collective pitch. Lowering the collective unloads the rotor, decreases the blade angle of attack, and lets rotor RPM recover. As the rotor speed comes back up, the stall breaks and control is regained. Once stable, smoothly apply forward cyclic to increase airspeed and reestablish translational lift, using coordinated pedals to maintain heading. Increasing collective would make the stall worse, and applying pedal or forward cyclic alone without unloading the rotor does not reliably recover from the stall.

Retreating blade stall happens when the blade on the retreating side of the rotor reaches a high angle of attack at low forward speed, causing a sudden loss of lift and a tendency to yaw and roll toward the retreating side. The quickest way to recover is to reduce collective pitch. Lowering the collective unloads the rotor, decreases the blade angle of attack, and lets rotor RPM recover. As the rotor speed comes back up, the stall breaks and control is regained. Once stable, smoothly apply forward cyclic to increase airspeed and reestablish translational lift, using coordinated pedals to maintain heading. Increasing collective would make the stall worse, and applying pedal or forward cyclic alone without unloading the rotor does not reliably recover from the stall.