On September 12, 2003, at 1600 central daylight time, a Bell 206-B3 helicopter, N12HT, registered to Go-Interests LLC., of Manvel, Texas, and operated by Go-Helitrans of Freeport, Texas, was destroyed when it impacted the water prior to an attempted takeoff from the Galveston 395 offshore platform located in the Gulf of Mexico. The commercial pilot and two of his passengers were uninjured, and one passenger sustained minor injuries. Visual meteorological conditions prevailed, and a company flight plan was filed for the 14 Code of Federal Regulations Part 135 on-demand air taxi flight. The flight was originating at the time of the accident and was destined for Freeport, Texas. The 19,000-hour pilot reported in the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2) that after startup, he rolled the throttle up to 70% and reached up to turn the generator on when the helicopter started "bouncing and seemed to be centered on the mast as the helicopter rocked on all four corners of the skids." He then verified the collective was all the way down. The helicopter began to spin and he was "unable to control it with the anti-torque pedals." The pilot stated he centered the cyclic and the "rocking" continued. He rolled the throttle back to flight idle and noticed the helicopter was going over the edge of the platform. Subsequently, he "rolled the throttle to full open as he pulled the collective." The pilot further reported he did not believe the helicopter developed full power prior to impacting the water. The helicopter landed upright on the water, and came to rest on its right side. The floats were not deployed prior to impact with the water. The pilot reported he had accumulated 1,320 hours in rotorcraft-helicopters, 402 hours of which were in the accident make/model. The pilot further reported he had flown 8 hours in the accident make/model helicopter within the previous 30 days of the accident. The NTSB investigator-in-charge obtained copies of passenger statements from Go-Helitrans. The first passenger, who was sitting in the front left seat, stated that when everyone was onboard and ready to depart, the pilot started the helicopter and it appeared to be at a high rpm. The passenger further stated at this point, without warning, the helicopter started to "skip" across the landing deck, spun around 360 degrees and went over the side of the platform. The helicopter hit the water on its "belly." The passenger added that he feels the accident was due to the pilot "revving up the helicopter too much upon start up." The second passenger stated that after everyone was inside, the pilot started the helicopter and began the startup and warm up procedures. All of a sudden, before the pilot could finish the start up procedures the helicopter began to spin and skip across the landing deck and went over the side. The passenger further stated that the helicopter did not make a "dead fall" but was "out of control." The third passenger stated that the pilot asked everyone if they were all ready, and to his memory, the pilot did not seem to "have completely gone through his preflight checks, further stating that the pilot did not call in, nor arm the floats when the helicopter began to spin and hop on the deck." The witness added that he "did not know if the throttle was too high or if it was a malfunction." Despite multiple attempts, the helicopter has not been located and is presumed to be destroyed.