Incident Details
The pilot initiated a high orbit maneuver with a takeoff into the wind. As the pilot began a right turn, described as "gently and smoothly," the helicopter experienced an uncommanded right yaw accompanied by a "high engine whine sound." At that moment, the pilot estimated the wind was at his 10 o'clock position.
Pilot Actions
In response, the pilot immediately applied left pedal to counteract the right yaw, but this did not stop the rotation. The pilot then lowered the collective and attempted to fly out of the condition by turning the helicopter into the direction of rotation. Despite these efforts, the helicopter completed three full 360-degree turns to the right. Subsequently, the pilot-in-command (PIC) closed the throttle to idle and performed an autorotation landing on a dry lakebed.
Background
FAA Advisory Circular 90-95 notes that maneuvers requiring high power and low airspeed with a left crosswind or tailwind can create conditions where unanticipated right yaw may occur. The AC also advises that susceptibility to loss of tail rotor effectiveness (LTE) is greater during right turns and that this phenomenon can occur in varying degrees in all single main rotor helicopters at airspeeds below 30 knots.