On October 14, 2003, at 1556 mountain standard time, a Mooney M20K, N5659L, operated by the pilot, was substantially damaged during a hard landing at Walker Field (GJT), Grand Junction, Colorado. The airline transport certificated pilot, and an airline transport certificated passenger, were not injured. Visual meteorological conditions prevailed. No flight plan had been filed for this local flight being conducted under Title 14 CFR Part 91. The flight originated at approximately 1530. According to the pilot, he had completed an uneventful touch-and-go landing on runway 29 using an approach speed of 67 knots. On the second touch-and-go landing, he used an approach speed of 70 knots. The airplane's airspeed was stable around the pattern. Just short of the runway, at approximately 30 feet agl, he encountered a slight "burble." He initiated full power, and as he dropped the nose of the airplane a few degrees, he encountered a second "burble." The pilot stated that "the airplane literally fell out of the sky" and struck the runway. The impact with the runway separated the right main landing gear and the separated right main landing gear struck the right horizontal stabilizer. The nose landing gear collapsed, the right wing tip and propeller struck the runway, and the airplane slid approximately 150 feet. The airplane sustained substantial damage to the right wing spar and the right horizontal stabilizer. At 1553, the reported weather at Walker Field (elevation 4,858 feet msl) was: wind, 310 degrees at 8 knots; visibility, 10 statute miles; sky condition, clear; temperature, 19 degrees C.; dew point, minus 17 degrees C.; altimeter setting, 30.08. The calculated density altitude was 6,327 feet msl. At 1604, the reported weather at Walker Field was: wind, 280 degrees at 5 knots; visibility, 10 statute miles; sky condition, clear; temperature, 19 degrees C.; dew point, minus 16 degrees C.; altimeter setting, 30.07. The calculated density altitude was 6,336 feet msl.