Accident
A single-engine aircraft performing a banner tow operation completed its flight and entered a downwind traffic pattern for the banner release area. While on downwind, the engine began to run rough and lost power. The pilot moved the mixture control to full rich and pumped the throttle. The engine briefly regained power before stopping completely.
At approximately 600 feet above ground level, the pilot decided against attempting an engine restart. He released the banner and performed a forced landing into the wind on a freshly plowed field. During the landing roll, the aircraft's right main landing gear collapsed, causing the aircraft to ground loop.
Investigation
Following the accident, the aircraft was transported to the airport. The engine was run without incident and was capable of producing full power. Inspection revealed that the flame tube located in the aircraft's muffler system was disintegrating. Investigators suspected that pieces of the flame tube may have blocked the muffler outlet, but the malfunction could not be duplicated during ground testing.
Probable Cause
The official investigation did not state a probable cause for the accident.