Tail Rotor Aerodynamics

Front 1

Define Loss of Tail Rotor Effectiveness?

Back 1

Inability of the tail rotor to provide sufficient force to maintain yaw
controllability.

Front 2

When does LTE occur?

Back 2

When full pedal input is insufficient to
provide directional control.

Front 3

What factors influence LTE?

Back 3

Relative wind direction, low speed/high power maneuvering, operating rpm, gross weight, and DA are several factors that can contribute to LTE.

Front 4

How do winds from the right affect LTE?

Back 4

Winds from the right tend to decrease angle of attack of the tail rotor for a given pitch setting, reducing effectiveness and requiring additional
left pedal to maintain heading. Additional left pedal depletes main rotor power and reduces directional control authority. When operating in
high power, right crosswind situations, tail rotor effectiveness may be lost.

Front 5

How do winds from left affect the tail rotor?

Back 5

Winds from the left will tend to increase angle of attack on the tail rotor for a given pitch setting and may increase tail rotor effectiveness. However, if the left wind component is excessive, disturbed airflow around
the tail rotor may develop resulting in loss of effectiveness.

Front 6

What is the weathervaning region?

Back 6

Winds within the region of 120° to 240° relative will tend to weathervane the nose of the aircraft into the wind.

Front 7

What is the TR vortex ring state region?

Back 7

210° to 330° relative. This vortex ring state causes tail rotor thrust variations that can initiate yaw rates.

Front 8

When does main rotor vortex ring state interaction occur?

Back 8

Winds within the region of primarily 280° to 330°, and less frequently from 030° to 080°, can cause the main rotor vortex to be directed onto the tail
rotor resulting in changes in angle of attack to the tail rotor.

Front 9

What is the result of loss of translational lift?

Back 9

Loss of translational lift results in increased power demand and additional antitorque requirements.

Front 10

What happens if you lose translational lift in a right turn?

Back 10

If the loss of translational lift occurs when the aircraft is in a right turn, the right turn rate will be accelerated if corrective action is not taken. When operating near maximum power available, this increased power demand could result in rotor rpm decay.

Front 11

What factors increase likelihood of LTE?

Back 11

1. conditions requiring higher main rotor power (e.g., high gross weight, high DA, or arresting a high descent rate).
2. Low airspeeds
3. Rapid application of collective can cause Nr droop. Low Nr with left pedal application can cause loss of directional control as tail rotor rpm decays.

Front 12

What are the steps to recover from LTE?

Back 12

A correct and timely response is critical.
1. Altitude permitting, lower the collective.
2. Increase airspeed and, if necessary, turn in direction of rotation.
3. At very low speeds or in a hover,
apply full left pedal.