On October 29, 1993, approximately 1635 central daylight time, a Bell 206L-3, N5370V, impacted the South Pass 49B helideck, located in the Mississippi Canyon 63 block, Gulf of Mexico, during takeoff. The pilot was not injured, but the aircraft was substantially damaged. Visual meteorological conditions prevailed, and a company VFR flight plan had been filed. The following is based on the Pilot/Operator accident report. Due to the high wind, the helicopter was tied down on the oil rig's helideck with four ropes. During preparations for takeoff, the left front tie down rope was inadvertently left fastened because of the high wind conditions and time constraints. The pilot lifted the helicopter off the deck and made a left turn into the wind. He felt a slight tug, but thought it was due to the turbulence. At a height of about two or three feet, the nose pitched abruptly down and the pilot felt "two quick mast bumps." His corrective control input and the helicopter's attitude caused the main rotor blades to contact the tailboom, severing the 90 degree gear box. The helicopter then spun 180 degrees to the right and impacted the helideck on its left side.