NTSB Identification: LAX91LA389.
The docket is stored on NTSB microfiche number 45770.
Accident occurred Wednesday, September 11, 1991 in HESPERIA, CA
Probable Cause Approval Date: 05/03/1993
Aircraft: CESSNA 172P, registration: N97564
Injuries: 3 Serious.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

DURING THE INITIAL CLIMB, THE PILOT EXPERIENCED A LOSS OF ENGINE POWER, AND WAS UNABLE TO CONTINUE TO CLIMB OR MAINTAIN ALTITUDE. THE PILOT STATED TO FAA INSPECTORS THAT HE CHANGED FUEL TANKS AND ADJUSTED THE MIXTURE TO NO AVAIL. HE LANDED STRAIGHT AHEAD INTO UNSUITABLE TERRAIN AND NOSED OVER. INVESTIGATION DETERMINED THAT NUMBER 2 CYLINDER EXHAUST VALVE HAD STUCK OPEN FROM CARBON BUILD UP. A MANUFACTURERS SERVICE BULLETIN REGARDING THIS POSSIBLE PROBLEM HAD NOT BEEN ACCOMPLISHED AT THE RECOMMENDED TIME, NOR WERE OTHER ITEMS OF IN SERVICE INSPECTION/INFORMATION REGARDING VALVE STICKING ADDRESSED ACCORDING TO THE RECORDS AVAILABLE.

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

A STUCK EXHAUST VALVE DUE TO THE OPERATOR'S NON COMPLIANCE WITH A MANUFACTURERS RECOMMENDED SERVICE BULLETIN ON THE ENGINE. CONTRIBUTING TO THE ACCIDENT WAS THE LACK OF SUITABLE TERRAIN FOR A SAFE LANDING.

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