Cirrus Design Corp SR22T N164CP accident near Minot, North Dakota

Probable cause

The failure of the Nos.2, 4, and 6 cylinders due to detonation.

NTSB analysis

During a cross-country flight, about 50-miles from the destination airport, the engine began to run rough. The pilot continued toward the airport and tried to resolve the engine issue. The No. 6 cylinder dropped offline, followed by the Nos. 2 and 4 cylinders. The engine was still running, but the pilot could not maintain enough altitude to make it to the airport. The pilot executed a forced landing in a snow-covered field. The airplane nosed over during the landing, which resulted in substantial damage to the engine firewall.

Downloaded engine monitoring data showed the No.6 cylinder stopped operating, followed by the Nos. 2 and 4 cylinders, consistent with the pilot’s statement. Oil was found on the belly of the airplane during initial examination. The data showed that the cruise power setting during the accident flight was 0.1 inches of mercury above the maximum cruise power setting listed in the flight manual. The recorded fuel flow was also above that expected for the maximum cruise power setting at the altitude flown.

During detailed teardown examinations of the engine, all six piston heads were found with various degrees of pitting damage. The most significant damage was found on the No. 2, 4, and 6 pistons. The damage found was consistent with detonation. The connecting rods exhibited thermal damage and the oil sump and oil filter contained aluminum particles. The fuel distribution spider valve and the fuel injectors were found normal and not obstructed. The metal fragments from the piston heads most likely obstructed the oil journals in the crankshaft and prevented oil from reaching the connecting rods and bearings. Thermal damage found within the rods and bearings of the engine likely resulted from the oil starvation.

Review of the engine logbooks did not reveal any uncorrected mechanical defects.

The loss of engine power was likely due to detonation that damaged the piston heads and resulted in their subsequent failure.

Text from the NTSB. Open the NTSB docket for CEN22LA144 for the full record.