NTSB Identification: LAX95FA225.
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Nonscheduled 14 CFR
Accident occurred Monday, June 26, 1995 in HIGHLAND, CA
Probable Cause Approval Date: 03/21/1996
Aircraft: HUGHES 369D, registration: N1089N
Injuries: 1 Serious,3 Minor.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

The helicopter pilot was operating in mountainous terrain with three doors removed. He was positioning survey personnel to remark survey sites. During departure from the mountainous terrain the pilot briefly noticed something in his skid mounted mirror. At that point, the pilot and the three passengers heard a loud 'whump' followed by a loss of tail rotor control. The pilot maneuvered the spinning helicopter over some power lines and onto a downward sloping ridgeline. The helicopter landed hard and rolled down the mountain about 100 to 150 feet. The tail rotor blades, along with half of the severed gear box were not recovered. The left rear seat passenger was missing a sweat jacket. An abundance of 12-inch reinforced marker tape was found at the accident site. Metallurgical analysis revealed that a high strain rate crack growth had occured as in a one-time overload on the tail rotor gearbox casting.

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

the pilot's failure to verify the security of his passenger's cargo/personal belongings which departed the aircraft striking the tailrotor.

Full narrative available

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