WPR23LA031

The pilot was enroute during a cross-country flight when the engine began running rough. He attempted to land in a clearing, but the airplane collided with trees and came to rest inverted before reaching the desired landing area. Postaccident examination of the engine revealed that the No. 1 cylinder exhaust valve had separated and was imbedded in the face of the No. 1 piston, cracking the piston. A portion of the intake valve was missing, and a portion of a valve was recovered inside the heat exchanger. Either a failed intake or exhaust valve would have resulted in a partial loss of engine power, but damage to the No. 1 piston and its intake and exhaust valves prevented determination of the initiating failure within the cylinder.

On November 11, 2022, about 1207 mountain standard time, a Cessna C-150 airplane, N3131J, was substantially damaged when it was involved in an accident near Star Valley, Arizona. The pilot was seriously injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The airplane was the second airplane in a flight of two that departed Phoenix Deer Valley Airport (DVT) Phoenix, Arizona, at 1115 with a planned destination of Gallup Municipal Airport (GUP), Gallup, New Mexico. The pilot stated he was climbing over rising terrain and about 1,000 ft above the ground when the engine started running rough. He applied carburetor heat and manipulated the engine controls, but the engine did not respond, and the engine rpm continued to decrease. He attempted to land in a clearing but collided with trees before reaching the desired landing area. The airplane came to rest inverted. The engine was examined and damage consistent with metal-to-metal contact was observed to both the top and bottom spark plugs of the No. 1 cylinder following their removal. The No. 1 cylinder was removed, and the exhaust valve and a portion of the intake valve were found to have separated from their valve stem and valve face, respectfully. The exhaust valve was imbedded in the piston face and the piston was cracked. A portion of an intake valve was recovered inside the heat exchanger. Damage to the exhaust valve and piston precluded additional examination to determine the failure mode of either valve. At the time of the accident, the engine had accumulated about 993 hours since overhaul and about 32 hours since the last annual inspection that was completed on May 13, 2022.