Incident Overview
On May 18, 2013, at approximately 1230 central daylight time, a Piper PA-28-161 airplane, registration N47539, experienced a loss of engine power during cruise flight. The pilot performed a forced landing in a field near Oskaloosa, Iowa. The airplane was registered to and operated by a private individual under 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed, and the flight operated without a flight plan. The flight departed from Washington Municipal Airport (KAWG), Washington, Iowa, around 1200.
Pilot Actions
According to the pilot, during cruise he felt a slight “bump” in the engine. He switched fuel tanks and turned on the fuel boost pump. The engine rpm dropped to about 1,500. He checked the magnetos, applied carburetor heat, and switched back to the first fuel tank; the engine did not respond. When the engine rpm decreased to 1,000, the pilot determined they could not reach an airport and selected a field for landing. During the landing, the airplane impacted a berm and came to rest on its belly.
Post-Accident Examination
A Federal Aviation Administration (FAA) inspector examined the airplane at the site. The landing gear had collapsed, and the fuselage sustained substantial damage. An A&P mechanic, under FAA supervision, subsequently examined the engine. The compression, fuel, and ignition systems were checked. The electric-driven fuel pump appeared to operate when activated; the carburetor bowl was empty of fuel, and minor debris was found in the inlet screen. The spark plugs were worn but fired on the left magneto when the engine was rotated by hand. The intake box was crushed during the accident, but the heat cables were operational. No anomalies that would have precluded normal engine operation were noted.
Carburetor Icing Assessment
The carburetor icing probability chart in FAA Special Airworthiness Information Bulletin No. CE-09-35 indicated that the aircraft was operating in conditions associated with a serious risk of carburetor ice at glide power settings.
Conclusion
A definitive reason for the loss of engine power was not determined.