FH.II.D.K9

From the FAA library

• Helicopter Flying Handbookp. 11-10
  Chapter 11: Helicopter Emergencies and Hazards › Retreating Blade Stall

  Excessive decrease of collective. Common Errors—Vuichard Recovery 1. Excessive lateral cyclic 2. Failure to maintain heading Retreating Blade Stall In forward flight, the relative airflow through the main rotor disk is different on the advancing and retreating side ... blade speed on the retreating blade, and its high AOA cause a stall and loss of lift. Retreating blade stall is a factor in limiting a helicopter’s never-exceed speed (VNE) and its development can be felt…

• Helicopter Flying Handbookp. 11-15
  Chapter 11: Helicopter Emergencies and Hazards › Low Rotor RPM and Rotor Stall

  rotor rpm continues to fall, the rotor will eventually stall. Rotor stall should not be confused with retreating blade stall, which occurs at high forward speeds and over a small portion of the retreating blade tip. Retreating blade stall causes…

• Helicopter Flying Handbookp. 2-20
  Chapter 2: Aerodynamics of Flight › Forward Flight › Dissymmetry of Lift

  retreating blade normally limits the maximum forward speed of a helicopter. At a high forward speed, the retreating blade stalls because of a high AOA and slow relative wind speed. This situation is called retreating blade stall and is evidenced…

• Aviation Maintenance Technician Handbook - Airframep. 2-25
  Chapter 2: Aerodynamics, Aircraft Assembly, & Rigging › Forward Flight › Dissymmetry of Lift

  retreating blade normally limits the maximum forward speed of a helicopter. At a high forward speed, the retreating blade stalls due to high AOA and slow relative wind speed. This situation is called “retreating blade stall” and is evidenced ... vibration, and a rolling tendency—usually to the left in helicopters with counterclockwise blade rotation. Pilots can avoid retreating blade stall by not exceeding the never-exceed speed. This speed is designated VNE and is indicated on a placard…