Incident Narrative
During maneuvering for external load operations to a boat, the helicopter suddenly began to shake violently. The pilot immediately realized that the helicopter had struck the boat with the main rotor blades. He jettisoned the 50-foot longline, activated the skid-based emergency flotation system, and landed the helicopter on the water without further incident.
Post-Accident Examination
A post-accident examination revealed that the helicopter had struck the boat's mast. The two main rotor blades sustained substantial damage. The pilot reported that there were no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation.
Pilot's Additional Comments
The pilot further added that he should have measured the boat mast height prior to operation instead of visually estimating the height, and that a 100-foot longline should have been used instead of the 50-foot longline.