I have trawled the previous threads on the LTE issue and have posted the following summary for future reference. It is made up from the previous work of three authors, Nick Lappos, Arm out the Window and myself. Thanks/apologies to Nick and AOTW!
If you see the sections on recovery techniques and the contrasting symptoms, you might understand why the distinction is very important and why mis-labelling the issue is dangerous.
Here goes:
Loss of tail rotor control: You are not able to control the tail rotor pitch mechanism - it is a true emergency. This could be a stuck control (left pedal, right pedal, or centre) or it can be a total loss of thrust (broken drive shaft or gear box). It can occur on any helo, but is relatively rare. Part of the training on every helo.
Loss of tail rotor effectiveness (LTE): "Newly" discovered and named in the 80's after many accidents - in particular OH-58/B206 model, and is the cause of a significant percentage of those model's accidents. Although somewhat awkwardly named (as the tail rotor is still effectively working and must be providing thrust) LTE refers to what is thought to be an ingestion of main or tail rotor vorticey through the tail rotor which causes a rapid onset of yaw in the direction induced by torque that cannot be overcome by the application of full "power pedal". The yaw
rotation is typically high and can build up quickly enough to fool most pilots into believing they have experienced a loss of tail rotor thrust.! It forces a loss of directional control
while inside the normal envelope.
It is prevented by using very conservative flying techniques, and preparing recovery escape manoeuvres, or by re-designing the tail rotor to assure adequate thrust. The typical LTE involves an approach to a spot with moderate cross wind, and a loss of yaw control when the approach is terminated near the hover. Once entered, recovery is very difficult without descending, often ground contact is unavoidable.
Loss of Tail Rotor Authority (LTA): In this situation, the tail rotor does not produce enough thrust to counteract the torque/crosswind combination you require, your power pedal hits the stop, and around you go - though very
gently when compared to LTE or total loss of thrust. LTA can occur on almost any helicopter
when operated outside its normal envelope, typically when the rotor rpm is abused, or when very high torque is demanded. It is a symptom of mishandling the RRPM or Torque, not a separate cause.
It is prevented by pre planning weight/DA/power demands and carefully managing RRPM. Typical LTA events involve a takeoff or landing when the helicopter hits its engine topping, and the rotor rpm droops below the green arc, and subsequent Torque reaction overcoming the reduced tail rotor thrust even at max (maximum power pedal applied) causing a loss of yaw control. Recovery often can be made by lowering collective to recover rpm without significant descent, so that ground contact is often avoidable.
Apply that to this accident: it is not LTE!