Event
During cruise flight at an altitude of 9,000 feet, approximately 60 miles east of the destination, the pilot heard a "bang." The engine RPM and temperature gauges indicated a failure of the right engine. The pilot secured the right engine, declared an emergency to air traffic control, and landed without further incident.
Examination
Post-flight examination of the propeller shaft coupling revealed a fracture caused by a fatigue crack. The crack originated from the corner radius of a lubrication slot where it converges with the root of an inner spline. At the time of the failure, the engine had accumulated 6,010.2 total hours since overhaul.