Engine Seizure During Test Flight Leads to Forced Landing in Trees (N3445K)

Incident Overview and Pilot Report A pilot reported that the number two cylinder and piston had recently been replaced on the aircraft's engine. Following the repair, the pilot completed a preflight inspection and conducted a twenty-minute engine run-up. The pilot then departed for a test flight around the airport. During the climb, the engine began to slow down, prompting the pilot to initiate a turn back to the airport. While in the turn, the engine seized. The pilot stated that due to a lack of altitude, he was unable to reach a clear area and was forced to land in trees. ## Engine Examination Findings Examination of the engine revealed that the number two piston had seized in the cylinder. The number two cylinder's bore was reported to be 0.007 inch over standard, and the piston was 0.015 inch oversize. The piston was galled as a result of the engine seizure. The cylinder and piston used for the repair were used parts. The mechanic who had installed the parts reported that adequate clearances had existed.