On October 15, 2008, at 1600 eastern daylight time, an experimental amateur built, Steele John J ACRO Sport II, N896JC, collided with trees during a forced landing near Madison, New Hampshire (NH). The pilot and passenger were not injured, and the airplane incurred substantial damage. Visual meteorological conditions prevailed and no flight plan was filed. The airplane was operated by a private individual, under the provisions of Title 14 Code of Federal Regulations Part 91, as a personal flight. The pilot stated to the responding Federal Aviation Administration (FAA) inspector that he was about 50 minutes into the flight when he started to head back to Windsock Village Airport (NH69), West Opssipee, NH, where he kept the airplane. He was beginning his descent from 1500 feet when the engine did a "roll back", and lost partial power. The pilot adjusted the throttle, mixture, and carburetor heat but the engine went to idle and remained at that power setting. He attempted to land in a field; however, the airplane’s altitude was insufficient to make the field and he made a controlled landing into trees. The aircraft remained in the tops of the trees, allowing time for him and his passenger to climb out of the airplane and onto the ground. The airplane eventually settled to the ground. The airplane incurred substantial damage to the lower right wing and throughout its structure from the tree branches and trunks. The pilot reported no discrepancies with the engine or engine controls before the partial loss of power. Prior to the flight, the pilot stated he had fueled the airplane with 5 gallons of fuel, for a total of 19 gallons of fuel on board the airplane. On scene examination of the airplane by a FAA inspector revealed that the fuel tanks were approximately 1/3 full The pilot stated the airplane underwent a conditional inspection in September of 2008, at which time the airplane had a total time of 712 hours. The airplane’s maintenance records were never provided. A wreckage examination was conducted by a FAA inspector. The engine controls were found to operate freely and correctly throughout their full range of motion. The engine was disassembled and examined, and no evidence of any pre-accident anomalies were noted. The fuel tank was examined and approximately 5 1/2 inches of clean automotive fuel was found in the tank. The fuel shut off valve was found in the off position, and no fuel was found in any of the fuel lines. None of the fuel lines showed signs of any blockage, and when the fuel shut off valve was placed in the on position, fuel started flowing after about 4 seconds. The fuel filter bowl was disassembled and inspected, and the screen was found to be approximately 10 percent blocked. The carburetor drain plug was removed, and approximately 1 oz. of fuel was found in the bowl. The mechanical fuel pump could not be tested for operation, but fuel passage through the pump was confirmed. The nearest official weather reporting facility was the Eastern Slopes Regional Airport (IZG), Fryeburg, Maine, located approximately 16 miles to the northeast of the accident site. The 1554 surface observation was: wind 170 at 5 knots; visibility 10 statute miles; sky condition clear; temperature 17 degrees Celsius; dew point 6 degrees Celsius; altimeter 30.04 inches of mercury. Review of the FAA Special Airworthiness Information Bulletin (SAIB) CE-09-35 revealed “serious icing” at glide power for a temperature of 17 degrees Celsius, and a dew point of 6 degrees Celsius.