Accident
The pilot was repositioning the helicopter from an offshore helideck to allow another helicopter to land and refuel at the platform. As the helicopter lifted off, the pilot lost control. The helicopter impacted the safety fence and fell 161 feet to the water, where it sank.
Investigation
A pilot who had landed prior to the accident reported observing that the rear and right front tie down straps of the accident aircraft were removed. However, he did not notice whether the left front tie down was still attached. An examination of the offshore oil pumping station revealed that the right front and rear tie down straps were in a metal storage basket located on the edge of the helideck. The left front tie down strap was fully extended and still attached to its tie down point, lying randomly on the helideck and the damaged safety fence. The left forward tie down fitting, normally attached to the bottom of the fuselage under the copilot's seat, was missing and never found. The three insert fittings of this tie down were pulled out of the honeycomb panel in a manner consistent with a relatively vertical pull. Examination of the tie down strap did not reveal any definitive damage indicating overload.
Further Examination
The hydraulic pump, when tested, produced correct pressure and fluid flow. The hydraulic switch in the cockpit was found in the ON position. Flight control continuity was established. The helicopter had a gross weight of 3,866 pounds, and its center of gravity (CG) was within the allowable CG limits.