Houston, TX, USA
N8063R
Sikorsky S-76A
The commercial pilot completed a successful landing to a hover and taxied to a point on the airport ramp to complete the flight mission. While at a stable hover, while preparing to set the twin-engine helicopter on the ground, the aircraft entered an uncommanded spin to the right. The copilot stated that the helicopter made 3 full 360-degree turns to the right prior to making ground contact. Lateral forces due to the spin caused the left main landing gear to collapse and all 4 main rotor blades to contact the ground. The aircraft remained upright and the pilot, copilot, and all 8 passengers were not injured. On scene investigation by a Federal Aviation Administration (FAA) inspector revealed that the cowling that covered the first section of the tail rotor drive shaft had not been secured and had contacted the shaft severing it in two. The helicopter had recently had maintenance performed and the cowling was left unsecured. The flight crew failed to notice the loose cowling during their preflight inspection prior to departure.
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.
The failure by maintenance personnel to secure the tail rotor driveshaft cowling after performing maintenance which resulted in a loss of tail rotor control. A contributing factor was the pilot's improper preflight inspection of the tail rotor driveshaft area.
Source: NTSB Aviation Accident Database
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