On August 23, 2003, about 1200 central daylight time, a Bellanca 7KCAB single-engine tailwheel-equipped airplane, N8730V, registered to Four Winds Aviation, Inc., of Killeen, Texas, and operated by the pilot was substantially damaged when it impacted the runway following a loss of control while landing at Aero Country Airport (T31) near McKinney, Texas. The flight instructor and the commerical pilot receiving instruction were not injured. Visual meteorological conditions prevailed, and a flight plan was not filed for the 14 Code of Federal Regulations Part 91 instructional local flight, which departed T31 approximately 1130. The 5,057-hour certified flight instructor (CFI), who was providing dual instruction to a commercial pilot for tailwheel endorsement, reported in the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2) that he was demonstrating a forward slip to a landing when he "flared too high," and the airplane "stalled and impacted the runway." According to information received from the FAA inspector, who responded to the accident site, the left main landing gear buckled on impact, and the airplane slid on its nose 150 feet down the runway. The inspector also reported that the aileron control attach bracket was broken from the bellcrank at the lower center fuselage, the propeller struck the runway, and the horizontal seat straps were broken on the rear seat. At the time of the accident, the pilot reported clear skies, and the wind as light and variable. With a temperature of 33 degrees Celsius, field elevation of 792 feet, and an altimeter setting of 30.05 inches of Mercury, the investigator-in-charge (IIC) calculated the density altitude to be 3,468 feet.