Incident Overview
A helicopter equipped for aerial spraying was involved in a mishap while repositioning on the platform of a nurse truck. The pilot reported that during the pull-up maneuver, the aircraft experienced uncommanded rotation. Ground crew observed a piece of the helicopter separate, followed by a spin-down of the tail rotor. The aircraft then entered an uncontrollable rotation, causing the main rotor blades to strike an adjacent small tree stand. The helicopter impacted the terrain, resulting in the collapse of the right landing skid and a subsequent rollover onto its right side.
Mechanical Findings
Examination of the wreckage revealed that the piece that separated was a section of the tail rotor drive shaft. No other mechanical abnormalities were identified in the pilot controls, engine, or drive train.
Operational Conditions
Interviews with the pilot, passenger, and ground crew indicated that the approach and the pull-up for the second approach were conducted in downwind conditions.