Incident Overview
During a descent from cruise altitude, the pilot reported that the engine began surging. After adjusting the boost pump, throttle, and mixture controls, the surging ceased. The pilot continued the approach, lowering flaps and landing gear at 2,000 feet above ground level (AGL) and 5 miles from the airport. At that point, the engine began surging again. Further adjustments of the throttle and mixture did not resolve the condition. Subsequently, the engine lost all power. The pilot performed a forced landing in a wheat field, which was located approximately 3 miles from the intended airport.
Examination Findings
A post-accident examination of the engine revealed that the upper deck pressure reference line, which runs from the manifold to the left bank fuel injector nozzle assembly, was disconnected. The line was found stuffed underneath other hoses in the engine compartment. A hose clamp was discovered resting on a metal channel nearby.
Maintenance History
Review of maintenance records indicated that the alternator had been replaced 7.3 flight hours prior to the accident. The upper deck pressure reference line would have required disconnection to facilitate removal and replacement of the alternator.
Analysis
No probable cause was determined in the investigation. The disconnected line was identified as a condition that could affect engine performance, but the source does not state a causal link or contributing factor.