On June 6, 2006, approximately 0755 central daylight time, a single-engine Bell 206L-1 helicopter, N272M, registered to and operated by Air Logistics L.L.C., of New Iberia, Louisiana, was undamaged while on the ground with rotors engaged at offshore platform South Pass 57, in the Gulf of Mexico. A passenger approaching the helicopter in an attempt to board was seriously injured when he was struck by the tail-rotor blades. The commercial pilot and two other passengers were not injured. Visual meteorological conditions prevailed and a company visual flight rules (VFR) flight plan was filed for the 14 Code of Federal Regulations Part 135 on-demand domestic air taxi flight. Approximately 0607 the flight departed from its company base located near Houma, Louisiana, for a flight to West Delta 106 (WD106), an offshore platform in the Gulf of Mexico. The flight then picked up three passengers with the intent of transporting them around on their daily platform checks. The pilot reported that prior to departure from WD106, he asked his passengers if they had any questions on aircraft safety. He also said he had briefed and flown with these passengers before, and that the passengers indicated that they had no questions regarding safety or emergency equipment. At 0750, the flight landed on oil platform South Pass 57 (SP57). The pilot reported that he landed in the middle on the helideck with the nose of the helicopter into the wind, which he reported as being out of the northeast about 2-3 knots. With the helicopter idling, two of the passengers exited the helicopter and helideck by the stairs located on the northeast side of the platform. The 11,754-hour pilot reported that after approximately 5 minutes, one of the passengers reappeared from the Northeast stairway and approached the helicopter. As they were waiting for the second passenger to return, the pilot reported he "heard two thumps and thought someone was putting baggage in the cargo compartment." The passenger, who remained in the helicopter and seated in the front seat next to the pilot, reported that after landing the two other passengers got out and used "the stairs in the front of the helicopter." He further reported that after a few minutes one of the passengers returned, "[coming] up the stairs in front of the helicopter." That individual then told the pilot to shutdown the helicopter, because the other passenger had been struck by the tail-rotor. The passenger who got off the helicopter reported that after landing on the helideck, he and one other person proceeded down the northeast stairwell. He added that the nose of the helicopter was pointed towards that stairwell. After recording some pressure measurements below, the passenger said that he "came up the southwest stairs to the heliport, saw the tail-rotor, and went [back] down to the living quarters deck." He then crossed over to the other side of the platform, where he used the northeast stairs to return to the helideck. The passenger reported that as he approached the left side of the helicopter, he saw the other passenger "come up the southwest stairs." The passenger reported that he yelled to the other person to stop; however he was struck by the tail-rotor. He then notified the pilot who then moved the helicopter to the side of the helideck and shutdown the helicopter.