CEN22LA144

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.

On March 11, 2022, about 1605 central standard time, a Cirrus SR22T airplane, N164CP, sustained substantial damage when it was involved in an accident near Minot, North Dakota. The pilot and one passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that he was on a 1.5-hour cross-country flight from Fargo, North Dakota. Minot International Airport (MOT), Minot, North Dakota was his destination. About 50 miles from MOT, the engine began to run rough. The pilot troubleshot the rough engine and initially concluded that there was an issue with the magneto. About 10 - 15 miles from MOT, the pilot perceived that the other magneto started to run rough. The No. 6 engine cylinder temperature began to rise, and the engine continued to run rough. The No.6 cylinder then “dropped offline,” followed by the Nos. 2 and 4 cylinders. The engine was still running, but the pilot could not maintain enough altitude to land at MOT, so he executed an emergency landing in a field. The pilot landed the airplane in a snow-covered field about 2 miles from MOT. The airplane came to rest upright with the nose landing gear collapsed. Examination of the airplane revealed substantial damage to lower structural portion of the engine firewall. Engine oil was present on the belly of the airplane. The airplane was secured by a Federal Aviation Administration (FAA) inspector at MOT. The engine was removed and shipped to Continental Engines in Mobile, Alabama, for detailed examination. Downloaded engine monitoring data showed the No. 6 cylinder dropped offline, followed by the Nos. 2 and 4 cylinders, which was consistent with the pilot statement. The data also showed that during the cruise portion of the accident flight, the engine manifold pressure was about 30.6 inches of mercury, and the fuel flow was about 19.6 gallons per hour. According to the airplane flight manual, leaning of the engine was to be accomplished by either leaning until the target fuel flow displayed on the engine monitor was achieved, or by monitoring the turbocharger inlet temperature and leaning until the temperature was 50° to 75° on the lean side of the peak value. The recorded data did not reveal the target fuel flow; however, the flight manual indicated a normal fuel flow of 18.3 gallons per hour with the airplane at 6,000 ft altitude and 30.5 inches of mercury. Detailed teardown examination of the engine revealed various degrees of pitting damage to all six pistons heads. The most significant damage was found on the No. 2, 4, and 6 pistons, with the No 6 piston showing melting damage. 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 crankshaft and main bearings exhibited a slight amount of lubrication distress. The extent of damage found at the No. 6 piston wasconsistent with the lubrication distress found in the engine. The remaining internal engine components exhibited normal operating signatures. A review of the engine maintenance records did not reveal any uncorrected defects.