NTSB Identification: MIA96LA166.
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Accident occurred Friday, June 28, 1996 in LORIDA, FL
Probable Cause Approval Date: 04/03/1997
Aircraft: Bell UH-1B, registration: N9846F
Injuries: 1 Minor,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.

The tail rotor gearbox, hub, and blades separated from the helicopter during flight. The helicopter then began to spin to the right. The pilot reduced engine power and leveled the helicopter; however, it touched down moving sideways, and the main rotor contacted the ground. Postcrash examination of the gearbox showed the gear box mounting studs had failed due to bending fatigue, which was a result of the mounting bolts not being torqued properly. Logbook records showed the gearbox had been replaced 95 flight hours before the accident.

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

failure of company maintenance personnel to properly torque the tail rotor 90 degree gear box mounting bolts during installation, which resulted in failure of the mounting studs due to bending fatigue and subsequent separation of the gearbox.

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