CH.I.F.R7

From the FAA library

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

  altitude is increased, higher blade angles are required to maintain lift at a given airspeed. Thus, retreating blade stall is encountered at a lower forward airspeed at altitude. Most manufacturers publish charts and graphs showing a VNE decrease with altitude ... retreating blade stall condition caused by high airspeed, moving the cyclic aft only worsens the stall as aft cyclic produces a flare effect, thus increasing the AOA. Pushing forward on the cyclic also deepens the stall…

• 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…