What happened
During a seaweed harvesting operation, a pilot was engaged in off-loading a sling-load of bales when they first noticed a momentary vibration, described as a "buzz," originating from the tail rotor. This sensation vanished after the pilot applied yaw pedal input.
As the aircraft transitioned back toward the pickup location at approximately 200 feet amsl and a speed of 60 knots IAS, the airframe was suddenly struck by a high-frequency vibration accompanied by a loud noise. This was immediately followed by a sharp downward pitch of the aircraft's nose. An observer on the beach witnessed the tail rotor detach from the aircraft and fall into the sea, appearing to remain intact upon impact.
Following the separation, the pilot struggled to counteract a violent rotational movement. As the aircraft neared the shoreline, the pilot reduced throttle and applied full collective. The helicopter struck a group of rocks and subsequently rolled onto its side. The pilot, protected by a safety helmet and a full harness, escaped the incident uninjured.
The investigation
Investigators focused on the sequence of events leading from the initial transient vibration to the structural failure of the tail rotor. The investigation examined the mechanical state of the aircraft during the sling-load process and the subsequent flight phase, noting the witness account of the tail rotor separating from the airframe and falling into the ocean.