At high airspeed, the airflow from the helicopter’s forward movement may exceed the rotational speed of the retreating blade.
A retreating blade stall is when the retreating blade flaps down so significantly that the blade reaches its critical angle of attack and stalls.
Ground resonance is a vibration that can be destructive to a helicopter.
A dynamic rollover is a catastrophic event where rotor thrust pulls the helicopter sideways around a pivot point, such as from catching a skid on an object.
A vortex ring state is when the helicopter’s downwash recirculates into the induced flow and the helicopter descends while under power.
Loss of tail rotor effectiveness, commonly referred to as LTE, is when the ability to provide anti-torque thrust from the tail rotor is ineffective or highly unreliable.
More power is required for left pedal turns. If a left turn can be completed, there is enough power available to safely control the helicopter in the current flight conditions.
A ground reconnaissance is performed before an off-airport landing. The reconnaissance is intended to ensure that the aircraft can land safely at the designated location.
Vibrations are caused by out-of-balance forces. The source of the out-of-balance condition may be unequal rotor mass distribution, inadequate blade tracking, and or unbalanced drive train components.
Lower the collective to reduce drag and increase throttle for more power, if available. If in forward flight, gently apply aft cyclic.