NTSB Identification: LAX96LA150.
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Accident occurred Sunday, March 31, 1996 in SAN CARLOS, CA
Probable Cause Approval Date: 01/17/1997
Aircraft: LAMPERT REVOLUTION M500, registration: N750GL
Injuries: 1 Minor.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
According to FAA airman records, the pilot did not hold a rotorcraft category rating. FAA inspectors examined the pilot's logbook and reported that he received a solo endorsement in helicopters about 1 1/2 years ago. The pilot was returning to the airport following a local area flight. About 1 mile west of the airport, the pilot began to smell something burning and said he sensed something was wrong. Shortly thereafter, he heard a 'slap' sound as the helicopter transitioned through 50 feet and 50 knots about 1/4 mile from the runway. The pilot stated that he 'didn't do anything [with the controls] but keep it headed for an open area between the taxiway and the runway.' The pilot said he did not flare or touch the collective, and the helicopter hit hard in the open area and rolled on its left side. An FAA airworthiness inspector examined the helicopter and found the engine to transmission drive belt fragmented, with rubber transfer throughout the engine compartment. Rubber transfer on the pulleys showed a forward movement pattern of the belt off the pulley. The inspector reported that the pulley was designed without a flange or other means to keep the belt aligned.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: the pilot's failure to recognize a drive train disengagement and initiate an autorotation. The inadequate engine-to-transmission drive belt/pulley design, and the pilot's limited training and experience in rotorcraft operations were factors in this accident. Full narrative available
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