On October 8, 2013, about 0800 central daylight time, a Beech S35 airplane, N6861Q, owned and operated by a private pilot impacted trees and terrain ½ mile from the approach end of runway 13 at the Brownwood Municipal Airport (BWD), Brownwood, Texas, following a loss of engine power. The private pilot, the sole person on board the airplane, was seriously injured. A postimpact fire ensued and the airplane was substantially damaged. The personal flight was being conducted under the provisions of 14 Code of Federal Regulations Part 91 without a flight plan. Visual meteorological conditions prevailed for the flight which had departed Coleman, Texas, at 0745, and was en route to BWD. The pilot stated he was making a straight in approach to land when the accident occurred. He stated he was at an altitude of about 800 feet above ground level (agl) with the landing gear down, when the engine lost power. The pilot stated he did not notice any engine roughness or unusual sounds prior to the loss of engine power. He attempted to restart the engine, but was not able to regain power. The pilot stated the sun glare prevented him from seeing the terrain until he was about 150 agl. The airplane contacted mesquite trees, cactus, and the terrain, and immediately erupted into flames. The pilot suffered second and third degree burns, but was able to extricate himself from the wreckage. The postimpact fire consumed the fuselage. Both main landing gears were damaged and the nose gear was sheared off. One propeller blade was bent rearward and the other propeller blade was straight. The pilot purchased the airplane five days prior to the accident. The airplane had an annual inspection in July and a pre-buy inspection just prior to him purchasing it . The airplane had been flown 14 hours since the annual inspection. The pilot's logbook and the aircraft maintenance records were on the airplane at the time of the accident and were destroyed. The engine was examined on November 15, 2013. Evidence of a foreign material was present on the fuel pump vanes, the fuel manifold, and on the fuel metering unit inlet screen. No other anomalies were noted which would have prevented normal operation of the engine. The fuel metering unit fuel screen was sent to the National Transportation Safety Board Material's Laboratory for examination. A visual examination revealed a yellow-brown, slightly rigid material was adhered to the outer surface of the fuel screen. Small amounts of the material had flowed through the screen to the inner surface. The material was examined using a Fourier Transform Infrared spectrometer with a diamond attenuated total reflectance accessory. The infrared wavelength absorbance spectrum was a very strong match to the spectrum of polyester. The source of the material could not be determined.