On April 19, 2006, approximately 1720 central daylight time, a twin-engine Sikorsky S-76A helicopter, N8063R, registered to and operated by Houston Helicopters, of Pearland, Texas, was substantially damaged following a loss of tail rotor control while hovering at the West Houston Airport, (IWS) near Houston, Texas. The commercial pilot, copilot, and eight passengers were not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the 14 Code of Federal Regulations Part 135 air taxi flight. The final segment of the flight departed High Island 139 in the Gulf of Mexico at 1652, en route to IWS for mission completion The pilot reported in a written statement that he made a right pedal turn to land facing the airport's terminal building. The pilot added that all forward movement had stopped and he began lowering the collective to land when the aircraft entered an uncommanded spin to the right. The copilot stated that the helicopter made about 3 full 360-degree turns prior to making contact with the ground. After the aircraft made contact with the ground, the pilot reached up and retarded the power levers. When the aircraft came to rest, the flight crew shut-off the fuel and batteries and exited the aircraft with the passengers, unassisted. Examination of the helicopter by an Federal Aviation Administration (FAA) inspector, who responded to the accident site, revealed that the tail rotor drive shaft had been severed. The left main landing gear also collapsed on landing, and all 4 main rotor blades were damaged from contact with the taxiway. Examination of the severed drive shaft area revealed that dzus fasteners on the drive shaft cowling were not secured. Maintenance had recently been completed on the drive shaft. Preflight checks also require that the same area is checked and the loose fasteners were not noticed by the flight crew during his pre-flight preparations. At 1753, the weather at the Sugarland Regional Airport (GSR), approximately 12 miles to the south of IWS, reported wind from 130 degrees at 13 knots, visibility 10 statute miles, clear skies, temperature 28 degrees Celsius, dew point 20 degrees Celsius, and barometric pressure at 29.78 inches of Mercury.