Cessna 172M N20800 accident near Lakeport, California

Probable cause

Loss of engine power during climb due to a failure of the No. 2 piston assembly; the reason for the failure could not be determined because of the extent of damage to the piston assembly.

NTSB analysis

During the initial climb following takeoff, the engine began to make a rumbling sound. The pilot began a series of troubleshooting steps, and a short time later, the engine lost all power. The pilot performed a forced landing into a vineyard, where the airplane sustained substantial damage to both wings and the horizontal stabilizer.

Examination of the engine revealed catastrophic internal failure focused primarily in the area of the No. 2 piston. Following the failure, excessive heat developed within the engine, which caused the crankshaft to expand and impinge on the oil pump, which in turn failed. The damage sustained to the piston, connecting rod bearing, and connecting rod bolts, prevented an accurate assessment of the failure mode.

Text from the NTSB. Open the NTSB docket for WPR13LA224 for the full record.