What happened
The accident occurred while a Hughes 369D helicopter was engaged in Christmas tree external-load operations. During the operation, a choker attached to a long-line external hook became snagged on an unidentified object. The force of the snag caused the remote hook to snap and strike the main rotor system.
According to the pilot's account, the immediate reaction was to attempt a power-on autorotation to regain control. However, due to low rotor RPM at the time of impact, the main blades chopped off the tail boom, leading to the crash.
The investigation
The investigation focused on the mechanical failure of the external load system and its interaction with the aircraft's rotor assembly. Examination confirmed that the remote hook had been forcefully detached from the long-line setup after snagging an object, resulting in it striking the main rotor blades.
Findings
Contributing factors to the accident included:
- The choker attached to the long-line external hook snagging on an unidentified object.
- The subsequent snapping of the remote hook into the main rotor system.
- Low rotor RPM preventing effective recovery during the attempted power-on autorotation.
The primary causal event was snagged external load equipment damaging the main rotor system.