On August 3, 2011, about 1743 central daylight time, an Aero Commander S2R, N1735S, sustained substantial damage during a forced landing following a loss of engine power near Washington, Iowa. The pilot was not injured. The airplane sustained damage to both wings, the fuselage, and the engine. The aircraft was registered to and operated by Cat Aviation, Inc, of Walnut Ridge, Arkansas under the provisions of 14 Code of Federal Regulations Part 137 as an aerial application flight. Visual meteorological conditions prevailed for the flight, which was not operated on a flight plan. The local flight was originating from the Washington Municipal Airport (AWG), Washington, Iowa, when the accident occurred. The pilot reported that the airplane's engine stopped producing power during climb out after takeoff. The airplane impacted terrain as the pilot was attempting to avoid a house during the forced landing. According to maintenance records, the most recent maintenance performed on the airplane was an annual inspection on January 17, 2011. A postaccident examination of the airplane confirmed crankshaft and accessory system continuity. The magnetos and fuel system could not be tested due to impact damage. No preimpact anomalies were noted during the examination that would explain the loss of engine power.