On June 26, 2002, about 1150 eastern daylight time, a Grumman-American AA-1, N5684L was substantially damaged when it struck terrain during departure climb from York Airport (THV), York, Pennsylvania. The certificated private pilot and the pilot owner received minor injuries. Visual meteorological conditions prevailed for the personal flight. No flight plan had been filed for the flight that was conducted under 14 CFR part 91. According to interviews, the flight originated from Donegal Springs Airpark (N71), Marietta, Pennsylvania, with the pilot owner in the left seat manipulating the flight controls, and a private pilot occupying the right seat. After landing at York, the pilots changed seats for the return flight, with the pilot owner occupying the right seat, and the pilot in the left seat as the flying pilot. The private pilot reported that the air was very humid, and after the airplane became airborne, it was not climbing. The engine was running, and rising terrain was ahead of the airplane as the pilot maintained runway heading. The airplane settled into a corn field, with stalks about 4 feet high, and nosed over. The private pilot reported his airspeed was about 60 to 70 mph, and normally, the minimum climb speed for the airplane was about 80 mph. The pilot owner reported that prior to departure, he reminded the private pilot of the high temperature and density altitude. He then relaxed in the right seat. He thought the lift off was a little slow and again cautioned the flying pilot about his airspeed, and then turned his attention away from the cockpit. The pilot owner noticed the airplane had climbed to an altitude of 30 to 40 feet as it passed over a road, and the airplane was in a nose high attitude, and slow. He saw a wheat field ahead, which the airplane passed over, and further ahead, a corn field that was higher than the airplane. The airplane settled into the corn field and nosed over. The pilot owner reported that the normal climb speed for the airplane was about 85 to 90 mph. Both occupants reported that there were no mechanical problems with the airplane. According to a Federal Aviation Administration (FAA), inspector, the airplane owner held a private pilot certificate. According to FAA records, the airplane owner's last medical examination was July 13, 1995, and it was denied. A post accident examination of the airplane revealed damage to the firewall, landing gear, and both wings. According to a FAA inspector, the airplane was fueled with auto-gas; the screen in the carburetor was clear, the spark plugs were clean, and compression was obtained in all cylinders. The private pilot had departed to the north on runway 35, which was 5,188 feet long, 100 feet wide and had an asphalt surface. At 1153, the weather at York included variable winds at 3 knots, visibility 5 statute miles with haze, sky clear, temperature 30 degrees C (86 F), and dewpoint 23 degrees C (73 F). The density altitude was calculated to be 2,299 feet.