Which of the following describes the symptoms of retreating blade stall?

• A. Violent pitch-up of the nose; Tendency to roll toward the stalled (left) side
• B. Rapid yaw to the left with no pitch change
• C. Nose-down pitch with no roll
• D. Gradual loss of lift with minimal attitude change

Answer: (A)

Retreating blade stall happens in forward flight when the blade moving away from the direction of travel (the retreating blade) reaches a stall due to reduced relative wind, while the advancing blade still has more lift. When this occurs, lift on that side of the rotor disk collapses, creating a roll toward the retreating (stalled) side. The rotor disk also changes its attitude, causing the nose to pitch up abruptly. So the aircraft tends to roll toward the stalled blade and the nose rises quickly, often with the roll toward the left in many configurations. Other descriptions don’t match this combination of a sudden nose-up attitude and a roll toward the retreating/stalled side.