Incident Overview
A helicopter experienced a loss of tail rotor response while approaching an offshore platform, according to the pilot's report. The pilot opted to perform an autorotative emergency landing on the water. Witnesses observed the helicopter initiate an autorotation, then begin rotating to the left and pitching nose down. The helicopter entered a steep descent, and the pilot reported an inability to control the aircraft.
Emergency Descent and Water Impact
Prior to water impact, the helicopter assumed a level flight attitude and the emergency floats deployed. Upon striking the water, the helicopter rolled to the right and came to rest inverted in the water.
Maintenance Error Identified
According to the operator's maintenance superintendent, a mechanic either omitted a bolt's cotter key or installed it improperly. This error resulted in the disconnect of the tail rotor control rod assembly from the control lever located at the rear of the tail rotor gear box.
Conclusion
The investigation attributed the loss of tail rotor response to the maintenance oversight. No further details on aircraft type, registration, operator, or injuries were provided in the source.