Primary finding
Probable cause
A total loss of engine power due to fuel starvation. Contributing was the owner/builder’s inadequate maintenance.
Investigator assessment
Analysis narrative
The pilot reported that while enroute he noticed a slight rise in engine gas temperature (EGT) with a slight decrease in fuel consumption. Then engine power surged followed by a rapid decrease in power. The pilot performed a forced landing to the tundra and the airplane nosed over, resulting in substantial damage. Postaccident examination of the airplane revealed the fuel inlet screen into the fuel control unit was clogged, which prevented fuel from entering the engine. The pilot, who was the owner/builder, was unaware of the requirements to inspect and clean the fuel control inlet filter. The filter had been in operation for about 12 to 13 years before the accident. The installation service manual recommends that the owner/mechanic inspect and clean the fuel control inlet filter after break-in and at condition inspections or during annual inspections. The lack of maintenance of the fuel control inlet screen filter resulted in the screen becoming clogged and the subsequent fuel starvation.
Source record
Factual narrative
On September 16, 2023, about 1600 Alaska daylight time, an experimental amateur-built Murphy Moose SR 3500 airplane, N907W, sustained substantial damage when it was involved in an accident near Nenana, Alaska. The pilot was not injured. The airplane was operated by the pilot as a Title 14 Code of Federal Regulations Part 91 personal flight. Pilot reported that, while en route in a float-equipped airplane, he noticed a slight rise in EGT with a slight decrease in fuel consumption. The engine was operating normally, but the pilot noted at a slight reduction in power output. Then the engine power began to surge followed by a rapid decrease in power. The pilot made a left turn into the wind and towards a large lake to perform an emergency landing. About 200 ft above ground level the engine lost total power. The pilot stated he did not have sufficient altitude to land on the lake; he elected to perform a forced landing to the tundra. After touchdown, the airplane slid for about 75 ft and then nosed over, sustaining substantial damage to the fuselage and wings. Postaccident examination of the airplane revealed all the fuel lines from the gascolator to the engine fuel control unit contained fuel. The fuel inlet screen into the fuel control unit was clogged with fine nonmetallic debris which prevented fuel from entering the engine. The filter was installed about 12 to 13 years before the accident. According to the service manual, the filter should be cleaned after a break-in period, and then after every 50 hours of operation. The manual also recommends removing and cleaning the fuel filters during condition and annual inspections. The pilot, who was also the owner/builder, was unaware of the requirements to inspect and clean the fuel control inlet filter.