On August 6, 2014, about 1745 central daylight time, a Raytheon B36TC airplane, N1069T, made an emergency landing after a partial loss of engine power near the Decatur Airport (KDEC), Decatur, Illinois. The pilot was not injured and the airplane sustained substantial damage. The airplane was registered to and operated by S.R. Aero LLC, under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed for the flight, which operated on an instrument flight rules flight plan. The flight originated from the Macomb Municipal Airport (KMQB), Macomb, Illinois, at 1658. The pilot reported that he switched the fuel selector handle to the left fuel tank about 10 miles away from the airport. Minutes later while turning on a left base in the traffic pattern, he noticed a partial loss of engine power. He switched on the electric fuel pump and the engine power was briefly restored. The engine lost power again and the pilot made a forced landing into a corn field located on the south side of the airfield. During the landing roll, the airplane exited the corn field, struck a berm, and came to rest upright. The left wing partially separated from the fuselage and the firewall was damaged. The Federal Aviation Administration inspector, who responded to the scene, reported he retrieved 2 fuel samples from the airplane and both were clear of contaminants. A postaccident examination of the engine and airplane fuel system revealed fibrous debris was present in the fuel manifold valve and the filter screen, which measured 0.2 inches by 0.4 inches. Similar debris was found in the fuel selector screen, which covered most of the inside of the filter. A review of the airplane's maintenance records revealed that on April 12, 2014, an annual maintenance inspection was completed. During the inspection the left outboard fuel tank cell was replaced. The airplane's engine monitor data card was removed and sent to the NTSB Vehicle Recorder Division for download. The data card contained parameters for the accident flight which included manifold pressure, engine RPM, exhaust gas temperature, cylinder head temperature, fuel flow, oil temperature, and oil pressure. The data card revealed that the fuel flow signal was scattered from when the engine was brought up to takeoff power, with values in cruise flight that ranged from about 20 gallons per hour (GPH) up to about 95 GPH. In the final minute of the flight, the fuel flow decayed to 5 GPH, and spiked up to 75 GPH before it decayed a second time and did not return to previously recorded levels. The engine RPM tracked with the reduction and increase in fuel flow. The engine RPM decreased from about 2,125 RPM to about 1,580 RPM, and then spiked back up to 2,540 RPM for a short time before it decreased and did not return.