What happened
Approximately four hours into the flight, while performing a long descent toward the destination airport, the pilot experienced a gradual reduction in engine power. This reduction persisted for eight minutes and eventually led to a complete loss of engine power.
In an attempt to restore power, the pilot applied carburetor heat, but these efforts were unsuccessful. The pilot subsequently selected a nearby paved road for an emergency landing. During the landing roll out, the aircraft's right wing struck a road sign. This impact caused the airplane to swerve into an adjacent ditch, resulting in a nose-over.
The investigation
An examination of the aircraft failed to reveal any mechanical issues. Fuel was recovered from the fuel system for inspection. During a subsequent functional test of the engine, the powerplant operated normally across all power ranges.