WPR22LA316

The pilot was conducting a personal flight. During the initial climb after takeoff, the engine lost partial power, and the airplane was unable to maintain altitude. The pilot initiated a forced landing to a nearby field; during the landing roll, the airplane impacted uneven terrain and came to rest upright, which resulted in substantial damage to the left wing and fuselage. Postaccident examination of the engine revealed that the No. 2 cylinder exhaust valve exhibited signatures consistent with a stuck valve, including a buildup of carbon deposits, and the exhaust valve could only be moved out of the valve guide with a significant amount of force. No additional evidence indicated any pre-existing mechanical malfunction or failure that would have precluded normal operation. Thus, the stuck exhaust valve likely caused the partial loss of engine power.

On August 24, 2022, about 1118 Pacific daylight time, a Cessna 150H, N22507, was substantially damaged when it was involved in an accident near Nut Tree Airport (VCB), Vacaville, California. The pilot and passenger sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that, during the initial climb after takeoff from runway 20 at VCB, while the airplane was at an altitude of about 200 to 250 ft above ground level, the engine began to sputter, and the engine speed decreased to about 1,700 to 1,800 rpm. The pilot verified that the mixture and throttle were in the takeoff positions, but the airplane was no longer climbing, and the pilot had difficulty maintaining the airplane’s altitude. As a result, the pilot initiated a forced landing to an open field adjacent to the airport. During the landing roll, the airplane impacted uneven terrain and came to rest upright, resulting in substantial damage to the left wing and fuselage. Postaccident examination of the engine revealed that it was partially attached to the engine mount. The carburetor was separated from the intake spider. The upper spark plugs, and rocker box covers were removed, and the propeller was rotated by hand. Rotational continuity was established throughout the engine. Thumb compression was obtained on cylinder Nos. 1, 3, and 4. No compression was obtained on cylinder No. 2, which was removed for further examination. The No. 2 cylinder was intact and undamaged. The exhaust and intake valve springs were intact and oil coated, as were the intake and exhaust valve rocker arms. The valve springs and keepers were removed. The intake valve slid out of the valve guide freely, but the exhaust valve slid out of the valve guide with a significant amount of force. The exhaust valve stem exhibited carbon buildup along with the valve neck. White deposits were observed around the rim of the valve. The valve seat also exhibited carbon buildup. The intake valve stem exhibited carbon deposits on the neck of the valve and stem. The valve seat contact area showed no carbon buildup, but a slight amount of carbon build-up was observed on the valve rim. Examination of the airframe and engine revealed no additional evidence of pre-existing mechanical malfunction that would have precluded normal operation.