On July 7, 2004, at 1718 eastern daylight time, a Piper PA-12, N2489M, was substantially damaged after departing from the Jaffery Airport (AFN), Jaffery, New Hampshire. The certificated private pilot was seriously injured. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight conducted under 14 CFR Part 91. According to the pilot, upon arriving at Jaffery, he topped-off the wing tanks with approximately 13 gallons of aviation fuel. The pilot then started the airplane and taxied to runway 16 for departure. The takeoff "seemed normal," until the airplane felt like it was not climbing. The pilot observed that the rpm gauge needle was dropping, and checked the carburetor heat and mixture controls. Realizing there was not a suitable area ahead to land, the pilot elected to return to the runway. During the turn back to the runway, the airplane descended into trees. Witnesses observed the airplane arrive at the airport at 1655, and requested a top-off. After refueling the airplane, a witness observed the airplane depart from runway 16, and climb to 100 feet above the ground. The airplane then banked to the left, and descended into trees near the end of the runway. Examination of the engine and fuel system by a Federal Aviation Administration (FAA) inspector did not reveal any abnormalities. Fuel samples from the airport were examined and absent of debris. The temperature and dew point recorded at the airport, about the time of the accident were 80 and 52 degrees respectively. A review of a FAA carburetor icing probability chart placed the reported temperature and dew point in the "serious at glide power" area of the chart.