On December 31, 2002, about 1200 eastern standard time, a Socata TB 9, N136ER, was substantially damaged during an overrun, following an aborted takeoff at Huntingdon County Airport (MUU), Mount Union, Pennsylvania. The certificated private pilot was not injured. Visual metrological conditions prevailed for the planned flight to York Airport, York, Pennsylvania. No flight plan was filed for the personal flight conducted under 14 CFR Part 91. The pilot reported that he was departing on runway 22 at MUU. Runway 22 was 3,120 feet long, 80 feet wide, and consisted of gravel and turf. The pilot stated that during the takeoff roll, the runway was "soft and soupy," and the airplane did not accelerate properly. He was able to lift the nose gear and one of the main gears off the ground, but the airplane would not become airborne. The pilot then aborted the takeoff, the airplane overran the runway, and came to rest inverted in a ditch. The pilot added that he did not experience any pre-impact mechanical malfunctions with the airplane. The pilot further stated that the accident airplane usually became airborne after a ground roll of about 500 feet, on a paved runway with only one person on board. During the accident takeoff, the wheels didn't begin to break ground until approximately 1,000 feet beyond the approach end of the runway. The pilot added that about 1,600 feet beyond the approach end of the runway, he decided to abort the takeoff. However, the airplane skid on the soft ground, and overran the runway at a speed of approximately 35-45 knots. The pilot reported a total flight experience of approximately 100 hours; of which, about 85 hours were in the same make and model as the accident airplane. Examination of the wreckage by a Federal Aviation Administration inspector revealed damage to both wings, the nose gear, and the firewall.