Cirrus Design Corp SR22 N242MB incident near Lexington, North Carolina

Probable cause

Maintenance personnel's improper tightening of the crankcase through bolt nuts during reassembly of the engine at the last overhaul, which resulted in the failure of the crankshaft and the subsequent total loss of engine power.

NTSB analysis

The commercial pilot was conducting a personal cross-country flight. The pilot reported that, while en route to his destination at a cruise altitude of about 5,000 ft mean sea level, the engine "failed." He flew the airplane toward an open field and deployed the ballistic recovery parachute. He subsequently conducted a successful landing in the field.

An examination of the engine revealed that the crankshaft had fractured between the No. 2 main journal and the No. 2 connecting rod journal. An examination of the crankshaft revealed that the fracture was due to fatigue that had initiated from multiple origins at the fillet radius between the No. 2 main journal and the cheek at the aft end of the journal. The fatigue initiated from surface damage that occurred due to the No. 2 main bearing shifting. The bearing likely shifted due to the improper tightening of the crankcase through bolt nuts and subsequent insufficient clamping force of the crankcase saddle surfaces. A review of the airplane's maintenance records revealed that the engine was last overhauled 775 total flight hours before the accident, and no records were found indicating that the through bolts had been removed since that time. It is likely that maintenance personnel improperly tightened the crankcase through bolts during the overhaul.

Text from the NTSB. Open the NTSB docket for ERA15IA024 for the full record.