LAX99LA155

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.

On April 18, 1999, at 0914 hours Pacific daylight time, a Cessna 150H, N22710, owned and operated by the pilot, experienced a loss of engine power en route to Shelter Cove, California. The pilot made a forced landing in a wheat field near Yuba City, California. During rollout, the airplane encountered uneven terrain, nosed over, and was substantially damaged. The airline transport certificated pilot was not injured. Visual meteorological conditions prevailed during the personal flight, and a visual flight rules flight plan was filed. The flight was performed under 14 CFR Part 91, and originated from the uncontrolled Sutter County Airport in Yuba City, at 0856.

The pilot indicated to the National Transportation Safety Board investigator that he was familiar with the operation of his airplane. He holds a certified flight instructor certificate and reported having over 10,275 hours of flight time.

According to the pilot, following a normal takeoff he climbed to 2,000 feet mean sea level and began cruising toward his destination. After a few minutes, he felt a "bump," and the engine began losing power. However, no unusual vibrations were detected. The pilot stated that despite his application of carburetor heat and adjustment of the mixture control, the engine progressively lost all power until the propeller was eventually just windmilling.

In the pilot's completed report, he indicated that his airplane's total time was 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.

The Federal Aviation Administration coordinator verbally reported to the Safety Board investigator that an examination of the engine revealed its No. 2 cylinder exhaust valve was fatigued and broken. No other engine related malfunctions were observed.