Accident Overview
Following takeoff, the aircraft's engine lost power at approximately 2000 feet above mean sea level. The pilot executed a forced landing on an interstate highway, during which the aircraft sustained damage.
Post-Accident Examination
After the accident, the engine was tested and found to start successfully. However, it would lose power when accelerated above 1000 RPM. The Bendix servo fuel injector, model RSA-5AD1, was removed and bench checked. During bench testing, the fuel injector delivered only idle fuel flow.
Detailed Findings
Further examination of the fuel injector revealed that the elastic stop nut, part number 178491, had backed off from the fuel diaphragm assembly stem. This condition restricted the travel of the regulator, resulting in a lean fuel mixture.
Conclusion
The engine power loss was traced to the backed-off elastic stop nut on the fuel diaphragm assembly stem, which limited regulator movement and caused an excessively lean mixture.