Accident Details
During cruise flight, the engine crankshaft completely fractured, and the propeller separated from the airplane. The propeller subsequently struck the empennage. Witnesses reported that the airplane rolled to the right and impacted the terrain.
Damage Description
The propeller severed the rudder control cables, the left horizontal stabilizer and elevator, and the vertical stabilizer. The engine crankshaft was fractured between the crankshaft oil seal and the propeller flange. The propeller flange remained attached to the propeller hub assembly.
Investigation Findings
According to the NTSB Materials Laboratory Factual Report, "Bench binocular microscope examination of the fracture face revealed crack arrest marks typical of a fatigue cracking. The fatigue crack emanated from multiple origins at the external surface of the aft fillet radius from the propeller flange... ."
Maintenance History
The accident airplane had been involved in a propeller strike incident in which the propeller was damaged. The propeller was removed and sent for inspection and overhaul. According to the maintenance logbooks, a teardown inspection of the engine was not completed as required by Teledyne Continental Motors Service Bulletin SB-96-11. At the time of the accident, the engine had accumulated 573.6 hours since the propeller strike event.
Additional Information
No other relevant details were provided in the source.