What happened
The flight was proceeding in level cruise conditions during nighttime hours when the pilot first noticed sparks and visible flames emanating from the engine cowling. Shortly after this initial warning, the engine began to run roughly before completely seizing up.
After declaring an emergency with air traffic control, the pilot was cleared for a straight-in approach to a runway located approximately 28 miles away. However, upon assessing the situation, the pilot determined that the aircraft could not reach the airport. Consequently, an emergency landing was executed on an unlighted stretch of interstate highway.
During the landing roll, the right wing struck a guard rail. This impact caused the aircraft to veer sharply to the right, resulting in the collapse of the main landing gear.
The investigation
A thorough examination of the wreckage revealed that cylinder number three had separated into two distinct pieces. This separation was the direct result of a fatigue crack that had initiated at the inner diameter of the cylinder.
While the mechanism of failure was identified, investigators could not determine the specific cause of the initial fatigue crack. Evidence suggested that the crack had been present for some time, persisting for more than 26 hours since the last 100-hour inspection.