The helicopter tail rotor is needed to counter the thrust of the main rotor system. One type of emergency that can happen, causing the helicopter to lose tail rotor thrust, is LTE (loss of tail rotor effectiveness. This is not a mechanical problem, but instead it is the tail rotor getting caught up in a vortex ring state. It is important to be cautious when operating low speed with one of the dangerous winds (quartering front wind on the same side as the tail rotor, wind straight into the tail rotor, and a tail wind).
Other factors that can lead to LTE are low rpm, high gross weight, high density altitude, and fast pedal turns in the same direction as the main rotor is turning.
Recovery when hovering close to the ground is to conduct a hover auto by rolling off the throttle and cushion the landing with the collective. A hover auto will get rid of the torque immediately and the helicopter will cease to spin.
If you are at altitude, it will be necessary to move into clean (in any direction) air with forward cyclic.
Like us on FB at: https://www.facebook.com/ClevelandHelicopterServices/
Subscribe to Your YouTube channel and click the bell for notification of new training videos: https://youtu.be/RJstyarDbic