NTSB Identification: LAX99LA234.
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Accident occurred Tuesday, July 06, 1999 in SAN LUIS OBISPO, CA
Probable Cause Approval Date: 04/06/2001
Aircraft: Piper PA-28-181, registration: N3477Q
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 instructor and student obtained an instrument departure clearance to climb to VFR on top for a cross-country flight. After reaching VFR on top, the engine rpm decreased to about 1,800 and then to 1,500. Following unsuccessful attempts to restore power, the instructor descended through the stratus cloud deck and became VFR about 700-800 feet msl. The power level was insufficient to reach the airport and he landed in an open field. Examination of the carburetor revealed a fibrous material inside the throat similar to the lining found inside the intake duct. The duct had evidence of a prior carburetor fire, which had caused a deterioration of the duct. The last maintenance inspection on this rental aircraft was 50 hours prior to the accident.

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

A loss of engine power due to contamination of the induction system and the carburetor throat. Factors in the accident were a prior undetected carburetor fire, which caused a deterioration in the air duct material.

Full narrative available

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