NTSB Identification: SEA05LA163.
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Accident occurred Thursday, August 04, 2005 in Leavenworth, WA
Probable Cause Approval Date: 12/20/2005
Aircraft: Steele Safari, registration: N13MA
Injuries: 1 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.

While in cruise flight about 1,000 feet above ground level (agl), the pilot heard a loud grinding sound and felt a significant vibration in the airframe of the helicopter. The aircraft then swung to the right, so the pilot elected to reduce the throttle and perform an autorotation to a nearby open field. During the attempted autorotational landing on the soft grassy terrain, the aircraft touched down, bounced back into the air, turned about 300 degrees, and then touched down a second time. During the second touchdown, the aircraft rolled over onto its left side. During the accident sequence, the main rotor blades flexed downward and came in contact with the tail boom. When the pilot inspected the helicopter at the scene, he found that all of its components, except for the tail rotor drive shaft, were there at that one location. Although he searched the local area for the tail rotor drive shaft, he was unable to locate it. The drive shaft was later found by a local resident several hundred feet from the location where the helicopter touched down. After being recovered to a hangar, the aircraft was inspected by an FAA Airworthiness Inspector, who determined that the tail rotor drive shaft had failed in cruise flight at a location near where it attaches to the main rotor transmission assembly. The reason for the failure of the shaft could not be positively determined.

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

The failure of the tail rotor drive shaft during cruise flight. Factors include soft, grassy terrain at the location where the pilot executed the autorotational landing.

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