NTSB Identification: LAX00LA071.
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Accident occurred Tuesday, January 04, 2000 in CHANDLER, AZ
Probable Cause Approval Date: 11/25/2003
Aircraft: Rotorway Exec 90, registration: N89678
Injuries: 2 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 flight was a familiarization for the private pilot, who was transitioning into this model of helicopter. An approach was being made to runway 03 when the instructor heard a loud bang from the engine compartment behind his back at an altitude of 100 feet. He stated that it felt like all engine power was lost. When the instructor saw the rotor rpm decreasing, he took control and initiated an autorotation to a soft sandy area. During the touchdown, the main rotor blades contacted the tail boom, and the tail rotor blades contacted the ground. The operator reported that a subsequent inspection determined that the secondary drive shaft fractured. Laboratory examination concluded that the shaft failed from fatigue, originating from galling sites introduced during the manufacturing process. The operator reported that a temperature strip on the bearing was noted to be darkened before the flight, but they were unsure if this information was determined independantly by either the CFI or the student. All other shafts in the operator's fleet were inspected and no additional suspect shafts were found.

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

the fatigue fracture and separation of the secondary drive shaft, which resulted from the manufacturer's inadequate quality control process.

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