NTSB Identification: LAX96LA279.
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Accident occurred Friday, July 19, 1996 in HEALDSBURG, CA
Probable Cause Approval Date: 08/25/1997
Aircraft: Hiller UH-12E, registration: N124HA
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 pilot entered autorotation over unsuitable steep terrain and struck trees after observing split needles on the rotor/engine tachometer. The helicopter had a previous rotor-tach generator failure. The failure was attributed to a loose connection, and was allegedly repaired by the previous owner. The connection was found to produce intermittent and inaccurate instrument readings when the wire bundle was moved or flexed. The potting material within the electrical connector was found in poor condition.

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

The failure of the pilot to confirm a loss of power before entering autorotation after reading an erroneous instrument indication on the helicopter's dual tachometer. Factors in the accident were the erratic instrument, and maintenance personnel who failed to properly repair the system after the discrepancy was previously reported.

Full narrative available

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