Incident Overview
During a landing attempt, the pilot of a helicopter reported encountering loss of tail rotor effectiveness (LTE). The pilot stated that he maneuvered the aircraft toward an open field adjacent to the intended helipad. In the course of this maneuver, the tail rotor impacted a barbed wire fence.
Damage Sustained
The helicopter received substantial damage to the empennage as a result of the tail rotor strike. No other damage was reported.
Pilot Statement
The pilot indicated that there were no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation. He attributed the event to LTE.
Background on Loss of Tail Rotor Effectiveness
According to the Federal Aviation Administration's Helicopter Flying Handbook (FAA-H-8083-21A), loss of tail rotor effectiveness (LTE), also referred to as unanticipated yaw, is defined as an uncommanded, rapid yaw toward the advancing blade that does not subside on its own. The handbook emphasizes that LTE is caused by aerodynamic interaction between the main rotor and tail rotor, not by a mechanical failure. It notes that some helicopter types may be more prone to LTE due to the certification thrust produced by the tail rotor.