What happened
Following the replacement of the number two cylinder and piston, the pilot performed a preflight inspection and a twenty-minute engine run-up. The pilot then departed on a test flight intended to circle the airport. During the climb phase, the engine began to lose power, prompting the pilot to initiate a turn back toward the airport. While executing this turn, the engine seized. Due to insufficient altitude, the pilot could not reach a clear landing area and was forced to land the aircraft in trees. The pilot was not injured.
The investigation
An examination of the engine determined that the number two piston had seized within the cylinder. Investigators found that the bore of the number two cylinder was 0.007 inch over standard, while the piston was 0.015 inch oversize. The piston exhibited galling resulting from the seizure. Both the cylinder and the piston used in the repair were identified as used parts. Although the mechanic who installed the components reported that adequate clearances had been present, the mechanical failure occurred during the flight.