Incident Overview
A helicopter, registration N2138Y, departed Cameron, Louisiana, after refueling, en route to an offshore oil rig. Shortly after departure, while flying over water, the aircraft began to yaw and vibrate severely. The pilot reported that the tail rotor pedals "kicked" hard when additional power was applied. The aircraft then started to spiral and tuck to the right. In response, the pilot deployed the floats and closed the throttle in an effort to cushion the impact.
Post-Examination Findings
Examination of the tail rotor blade revealed that the blade tip counterweight had separated, causing a severe dynamic imbalance. The separation was due to debonding of the weight block and the bladeskin that had occurred sometime prior to the flight. Further examination of the tail rotor gearbox disclosed evidence of fatigue fractures of the gearbox attachment stub.
Aircraft and Flight Information
The flight originated from Cameron, Louisiana, with an intended destination of an offshore rig. No information regarding the number of occupants, injuries, or damage to the aircraft was provided in the source. The time of day, weather conditions, and air traffic control involvement were not specified.