Flight Instructor for Rotorcraft Category Helicopter Rating › XI. Emergency Operations › Task F. Vortex Ring State (VRS)

HI.XI.F.R6

Risk management

Loss of tail rotor effectiveness (LTE).

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Get a short, cited explanation of this element written from the FAA handbooks: the core idea, the numbers that matter, common test traps, and a quick self-check.

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Helicopter Flying Handbook p. 11-18
Chapter 11: Helicopter Emergencies and Hazards › System Malfunctions › Loss of Tail Rotor Effectiveness (LTE)
throttle may be decreased as well if it is not already at flight idle. Loss of Tail Rotor Effectiveness (LTE) Loss of tail rotor effectiveness (LTE) or an unanticipated yaw is defined as an uncommanded, rapid yaw towards the advancing ... aircraft if left unchecked. It is very important for pilots to understand that LTE is caused by an aerodynamic interaction between the main rotor and tail rotor and not caused from a mechanical failure. Some helicopter types are more likely…
Helicopter Flying Handbook p. 11-9
Chapter 11: Helicopter Emergencies and Hazards › Vortex Ring State
helicopter begins to descend vertically, it settles into its own downwash, which greatly enlarges the tip vortices. In this vortex ring state, most of the power developed by the engine is wasted in circulating the air in a doughnut pattern ... around the rotor. In addition, the helicopter may descend at a rate that exceeds the normal downward induced-flow rate of the inner blade sections. As a result, the airflow of the inner blade sections is upward relative…
Helicopter Flying Handbook p. 11-20
Chapter 11: Helicopter Emergencies and Hazards › System Malfunctions › Tail Rotor Vortex Ring State (210–330°)
left, depending upon the wind direction. If the pilot allows a right yaw rate to develop and the tail of the helicopter moves into this region, the yaw rate can accelerate rapidly. In order to avoid the onset of LTE ... imperative to maintain positive control of the yaw rate and devote full attention to flying the helicopter. Tail Rotor Vortex Ring State (210–330°) Winds within this region cause a tail rotor vortex ring state to develop. [Figure…
Helicopter Flying Handbook p. 11-20
Chapter 11: Helicopter Emergencies and Hazards › System Malfunctions › Main Rotor Disk Interference (285–315°)
Main Rotor Disk Interference (285–315°) Refer to Figure 11-9. Winds at velocities of 10–30 knots from the left front cause the main rotor vortex to be blown into the tail rotor by the relative wind. This main ... rotor disk vortex causes the tail rotor to operate in an extremely turbulent environment. During a right turn, the tail rotor experiences a reduction of thrust as it comes into the area of the main rotor disk vortex. The reduction…