Loss of tail-rotor effectiveness

Loss of tail-rotor effectiveness (LTE) occurs when the tail rotor of a helicopter is exposed to wind forces that prevent it from carrying out its function—that of cancelling the torque of the engine and transmission. Any low-airspeed high-power environment provides an opportunity for it to occur.

Environmental factors which can lead to LTE include higher operating-density altitudes or temperatures, and high winds. A high gross weight can also create an LTE-conducive situation. Causative wind-directions may include:

Many factors affect the onset of LTE, but no matter which way it occurs, the clues are present:

Recovery is initiated by increasing airspeed, using the vertical stabilizer to reduce yaw or, if uncorrectable by application of speed or tail-rotor thrust, entry into autorotation. Note that a full autorotative landing isn't necessary—the mere entry into autorotation will eliminate the torque, and then the spin or yaw will reduce through friction, particularly with the buildup of forward speed. At that point power recovery (while maintaining airspeed) can be successfully accomplished.

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