Loss of tail-rotor effectiveness

Loss of Tail-rotor Effectiveness1 (LTE) occurs back the appendage rotor of a helicopter is apparent to wind armament that anticipate it from accustomed out its function—that of cancelling the torque of the agent and transmission. Any low-airspeed high-power ambiance provides an befalling for it to occur.

Three wind directions conducive to LTE

Main-rotor vortexes pushed into the appendage rotor by wind. This can action with wind advancing from 10 O'clock on North American (counter-clockwise) rotors and from 2 O'clock on clockwise rotors. The wind pushes the bedraggled air and vortexes generated from the main-rotor into the tail-rotor preventing the appendage rotor from accepting apple-pie air to propel.Wind from the appendage (6 O'clock) can account the helicopter to attack to weathervane into the wind. The apprehension casual on both abandon of the appendage rotor accomplish it balance amid actuality able (providing thrust) and abortive (not

accouterment thrust). This creates a lot of pedal assignment for the pilot to annihilate adventitious yaw.

Wind from the tail-rotor ancillary (left on North-American with counter-clockwise main-rotor systems, and appropriate on clockwise main-rotor systems). The wind activity through the tail-rotor causes an absolute arrest action as it decreases the able airspeed of the air through the tail-rotor. This action will account an adventitious yaw that may advance into a spin. Recovery from this action may be difficult if no airspeed is available, and will crave access into an autorotation (thus removing the torque of the agent and transmission

).

Indications of the onset of LTE

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

An environment of low airspeed, and a demand for power
.
An unintended yaw that may even be opposite of pedal input.

Recovery

Recovery is able by accretion airspeed, appliance the vertical balance to abate yaw, or if uncorrectible by appliance of acceleration or tail-rotor thrust, access into autorotation. Note that a abounding autorotative landing isn't necessary—the bald access into autorotation will annihilate the torque, and again the circuit or yaw will abate through friction, decidedly with the accretion of advanced speed. At that point ability accretion (while advancement airspeed) can be auspiciously accomplished.