Incident Overview
A pilot reported that while in cruise flight, the airframe began to accumulate light rime ice. The pilot decided to return to the departure airport and was cleared to descend to a lower altitude. After descending, the engine was unable to maintain full power and began to run roughly. The aircraft could not sustain altitude to reach the airport, so the pilot elected to land in an open field.
Landing and Impact
During the gear-up landing on the soft field, the airplane collided with a berm and a barb wire fence. The aircraft was subsequently recovered.
Post-Accident Engine Examination
After recovery, the engine was determined to be in a condition suitable for a test run. A new propeller was installed, a battery was connected, and a fuel supply was rigged. The engine was started and ran normally at idle power until warmed up. It was then run to 1700 RPM, and a magneto check was performed. Oil temperature, oil pressure, exhaust gas temperature (EGT), and suction were all within normal parameters.
Inlet Air System Inspection
The inlet air box was severely damaged during the accident sequence. The alternate air door would operate only partway open; however, the hinge was clear and free. The air filter, a foam type, was in good condition with no sign of deterioration or blockage.