What happened
While cruising at 19,000 feet, a single-engine aircraft suffered a loss of engine power. The pilot notified air traffic control of the emergency approximately 16 minutes before the impact and requested permission to divert to the nearest airfield. Air traffic controllers provided vectors directing the plane toward Southwest Michigan Regional Airport (BEH) for an approach to runway 27.
During the descent, the aircraft's flight path and speed showed significant instability. Radar data indicated that between 9.5 and 5.3 nautical miles from the airport, the airspeed fluctuated between 119 and 155 knots, while the descent rate varied between 1,550 and 2,600 feet per minute. In the final stages of the approach, the airspeed decreased from 155 knots to 78 knots. Witnesses observed the plane spiraling toward the ground before the impact. The wreckage was discovered on the extended centerline of runway 27, roughly 1.12 nautical miles from the threshold, with a debris pattern suggesting a stall/spin accident.
Findings
An investigation into the engine components revealed that the crankshaft had fractured at the number five crankpin journal. A visual inspection of the part (p/n 13F27738, s/n V537920968) identified a fatigue-type fracture through the cheek, located aft of the fifth crankpin journal. While the specific origin of the fracture could not be identified due to mechanical damage at the initiation point, the fracture characteristics matched 14 other documented failures of this specific part number. The engine manufacturer concluded that these failures were likely the result of overheating the steel during the forging process.