N7103M

The pilot reported that the airplane's engine began to run rough during level flight with about a 70 percent power setting. He switched fuel tanks and applied carburetor heat, but the airplane's engine continued to run rough. The pilot initiated a forced landing to a cornfield during night light conditions. Postaccident examinations of the airplane revealed that the firewall was bent/buckled. No anomalies were found with regard to the airplane, engine, or systems during the postaccident examinations. A weather report for the destination airport recorded the temperature and dew point as 18 degrees Celsius and 16 degrees Celsius respectively. According to a Federal Aviation Administration Special Airworthiness Information Bulletin, entitled Carburetor Icing Prevention, the temperature and dew point were conducive to the formation of carburetor icing.