Incident Overview
A private pilot experienced a total loss of engine power while en route to the intended destination. Unable to reach a nearby airport, the pilot executed a forced landing in a field adjacent to a highway. The aircraft came to rest without further incident.
Investigation Findings
Examination revealed that the metering unit's throttle arm had become separated from the throttle cable during flight. This separation prevented the pilot from restarting the engine. Investigators found no evidence of metal deformation or gouging on either component, indicating that the separation was not due to mechanical overload or impact damage.
The lack of deformation suggests that a castellated nut with a retaining pin was either not installed or was improperly secured. Proper installation would have prevented the throttle arm and cable from disconnecting. The exact reason for the missing or inadequate installation could not be determined.
Conclusion
The engine power loss was directly attributable to the in-flight separation of the throttle linkage. The forced landing was successful, and no injuries were reported. The investigation focused on the hardware securing the throttle connection, but the circumstances leading to the improper installation remain unknown.