Incident Overview
A helicopter operated by an experienced pilot with 19,000 flight hours was involved in an accident during a platform operation. The pilot reported that after rolling the throttle up to 70% and reaching to turn on the generator, the helicopter began "bouncing and seemed to be centered on the mast as the helicopter rocked on all four corners of the skids." The pilot confirmed that the collective was fully down.
Loss of Control
The helicopter started to spin, and the pilot found he could not control the rotation using the anti-torque pedals. He centered the cyclic, but the rocking motion continued. Rolling the throttle back to flight idle, the pilot noticed the helicopter was moving toward the edge of the platform. He then "rolled the throttle to full open as he pulled the collective."
Impact and Sinking
The pilot stated he did not believe the helicopter developed full power before impacting the water. The helicopter landed upright on the water and subsequently came to rest on its right side. The floats were not deployed prior to impact. Despite multiple attempts, the helicopter has not been located and is presumed to be destroyed.
Additional Details
The helicopter's registration, operator, exact location, date, and number of occupants were not provided in the source. No injuries or fatalities were reported.