NTSB Identification: LAX99LA155.
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Accident occurred Sunday, April 18, 1999 in YUBA CITY, CA
Probable Cause Approval Date: 11/22/2000
Aircraft: Cessna 150H, registration: N22710
Injuries: 1 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.

While cruising, the pilot felt a 'bump,' and the engine began losing power. The pilot applied carburetor heat and adjusted the mixture control, but this action had no effect. The engine progressively lost all power until the propeller eventually just windmilled. The pilot made a forced landing in a wheat field. During rollout, the airplane encountered uneven terrain and nosed over. The pilot owned and operated the airplane. He reported that the airframe's total time was about 8,798.6 hours. The engine had been operated for 1,818.9 hours since being overhauled, and 133.4 hours since its last inspection. An examination of the engine revealed its No. 2 cylinder exhaust valve was fatigued and broken. No other engine related malfunctions were observed.

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

A total loss of engine power resulting from the fatigue failure of a cylinder's exhaust valve. A contributing factor was the uneven terrain at the forced landing site. The reason for the fatigue could not be determined.

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