CEN19LA320 · Cirrus SR22 Undesignat

The private pilot was conducting an instrument flight rules cross-country flight. While en route, the engine began to lose oil pressure, and the pilot diverted to a nearby airport. An inspection after landing revealed that the engine contained adequate oil and there was no evidence of oil leaking. The oil pressure and temperature indicated normally during a subsequent engine test run, and the pilot continued the flight to his destination. After about 40 minutes of flight, the engine abruptly lost total power and the pilot activated the airframe parachute system upon realizing that the airplane was not within gliding distance of an airport. The airplane came to rest upright in a field. The forward fuselage, two engine mounts, and both wings sustained substantial damage. The accident occurred about 2 months and 17 flight hours after the airplane's most recent annual inspection, during which the engine oil filter was cut open and no abnormalities were noted. The engine oil was subsequently changed about 1 month and 8.5 flight hours before the accident. The mechanic who performed the oil change reported that the engine was not equipped with a magnetic engine oil drain plug and that he did not cut open and examine the oil filter element, although the maintenance manual stated that oil screens and filter elements should be examined for contaminants at each oil change. The accident engine was equipped with a magnetic drain plug; however, postaccident examination revealed that the quick drain coupling and the magnetic oil drain plug were switched from their respective locations. Because of the switch, on removal of the plug to drain the oil, the mechanic most-likely wouldn’t have seen any indication of bushing material. Additionally, the manufacturer had issued a service bulletin advising that the magnetic drain plug be examined for recovered bushing material. A postaccident examination of the engine revealed that the No. 1 connecting rod separated from its piston and crankshaft and was found in the oil sump. Its bushing was not present; however, its piston pin was found in place. The No. 1 connecting rod bearing end components and sections of its bearing were found within the sump. Ferrous material was found on the magnetic oil drain plug and debris was found on the oil filter material. The piston pin bushings in the Nos. 2, 3, 4, and 6 connecting rods were displaced. The Nos. 2, 3, and 4 connecting rod bushings were chipped. The split lines for the Nos. 2, 3, and 4 bushings were found not clocked in accordance with manufacturer specifications. Although the reason for the piston pin migration could not be determined, it is likely that the impending migration and connecting rod failure may have been detected during the most recent oil change if the mechanic had followed the manufacturer's guidance to inspect the oil filter element and magnetic drain plug. Following the accident, the engine manufacturer issued a maintenance manual revision and a critical service bulletin that directed enhanced screening of oil and removing the non-magnetic oil plug or quick drain coupling and installing a magnetic drain plug in the oil sump to attract and collect ferrous wear particulate and larger particles.

Verbatim NTSB analysis and probable cause from the NTSB dataset