On December 9, 1996, at 1458 central standard time, an Aerospatiale AS350B, N390MA, registered to and operated by Metro Aviation, Inc., under Title 14 CFR Part 135, struck a crane while hovering at an offshore platform at the East Cameron 71 in the Gulf of Mexico. The commercial pilot and the sole passenger were not injured and the helicopter sustained substantial damage. Visual meteorological conditions prevailed for the flight and a company VFR flight plan was filed. The flight originated from West Cameron 238, Gulf of Mexico, at 1442. During telephone interviews and on the Pilot/Operator Report, the pilot and company personnel reported the following information to the investigator-in-charge. The helicopter approached the platform at an airspeed of 120 knots on a 190 to 200 degree heading. Winds were from the south at 10 knots gusting to 18 knots. The pilot hovered the helicopter about 3 feet above the helipad and initiated a pedal turn to keep the tailrotor clear of the stairwell and to align the helicopter into the wind for the landing. During the turn, the tailrotor struck a guard on the operator bucket of the crane and one tail rotor blade separated from the helicopter. The helicopter rotated uncontrolled through 90 degrees of heading change as the pilot rolled off the throttle and performed an autorotation onto the platform's helipad. The helicopter was examined by the pilot and other company personnel. Company personnel reported damage to the tailrotor blades, gearbox, and at the gearbox to tailboom attachment points.