On August 10, 2011, about 1750 central daylight time, a Grumman G-164A airplane, N127FC, was substantially damaged during a forced landing following a loss of engine power after takeoff near Mansfield, South Dakota. The pilot was not injured. The agricultural application airplane was registered to and operated by the pilot. The commercial flight was being conducted under the provisions of 14 Code of Federal Regulations Part 137. Visual meteorological conditions prevailed for the flight, which was not operated on a flight plan. The aerial application flight was originating from a private airstrip near Mansfield, South Dakota, at the time of the accident. The pilot reported that the engine began to lose power shortly after takeoff, without sufficient runway remaining to land. The engine gradually lost power completely and he executed a forced landing to a bean field about 1/4 mile from the departure end of the runway. The airplane sustained substantial damage to the wings and fuselage. A postaccident examination revealed debris in the engine air intake system. Debris was found in the carburetor heat section of the intake ducting, which appeared to have nearly blocked the duct completely. Debris was also found on the pressure side of the air filter, which appeared to have blocked about 25-percent of the duct cross section. The agricultural operator noted that the debris appeared to have been composed of paper towels; possibly as a result of rodent activity. The debris was located in an area of the intake ducting not visible during a preflight inspection. The engine was subsequently removed from the airframe and run in a test cell. No components were replaced prior to the test run. The air intake assembly from the airplane was not used because the test cell provided the intake duct work. The engine started without difficulty and ran to 1,500 rpm. The crankshaft appeared to have been bent slightly in the accident, so the engine was not run above 1,500 rpm for safety reasons. The engine was overhauled in March 2011 and installed on the accident airplane in May 2011. At the time of the accident, the engine had accumulated approximately 240 hours since the overhaul.