NTSB Identification: DFW06LA093.
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Nonscheduled 14 CFR
Accident occurred Wednesday, April 19, 2006 in Houston, TX
Probable Cause Approval Date: 06/27/2007
Aircraft: Sikorsky S-76A, registration: N8063R
Injuries: 10 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

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.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

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.

Full narrative available

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