Bellanca 17 30A N4204B accident near Blaine, Minnesota

Probable cause

A total loss of engine power due to a lack of crankshaft lubrication to the No. 4 connecting rod journal.

NTSB analysis

After dropping off two passengers on an extremely cold morning, the commercial pilot departed for the return flight home. During cruise flight at 2,500 ft mean sea level, the engine experienced a total loss of power. The pilot restarted the engine; shortly thereafter, the engine lost power a second time. The pilot executed a forced landing onto a road, during which the left wing was damaged.

An engine teardown revealed significant heat distress to the crankshaft No. 4 connecting rod journal, as well as the Nos. 3 and 4 connecting rod bearings. The heat distress resulted in fracture of the Nos. 3 and 4 connecting rod caps and subsequent seizure of the engine. The Nos. 1, 2, 5, and 6 connecting rod bearings exhibited overlay fatigue, dirt embedment and corrosion, consistent with inadequate oil lubrication. A review of the engine maintenance logbooks revealed a history of oil changes at inconsistent intervals, which included much longer intervals than those recommended by the manufacturer; however, the effect of the inconsistent maintenance could not be determined based on the available information.

Text from the NTSB. Open the NTSB docket for CEN17LA058 for the full record.