Accident Description
The pilot was maneuvering a helicopter to land on an offshore platform. The initial approach was from the north, heading into a south-southeast wind of 20 to 25 knots. The pilot then began a right turn to circle clockwise around the platform at an altitude of 300 to 400 feet above ground level and an indicated airspeed of 70 to 80 mph.
Approximately three-quarters of the way around the platform, the helicopter "began to spin" to the right. The pilot applied left pedal in an attempt to stop the spin, but reported "no tail rotor response." Subsequently, the pilot "made an effort to try to come out of [the spin] by lowering the collective and dropping the nose of the aircraft." These control inputs had no effect on stopping the spin, and the helicopter descended and impacted the water.
Background
No anomalies were reported with the tail rotor system prior to the accident. In February 1995, the Federal Aviation Administration (FAA) issued Advisory Circular (AC) 90-95 concerning unanticipated right yaw in helicopters, or loss of tail rotor effectiveness (LTE). The advisory circular notes that LTE may occur in right turns at low airspeeds and emphasizes that correct, timely response is critical to prevent a loss of control.
Conclusion
The investigation did not determine a probable cause for the loss of control.