On May 28, 2007, about 1630 Pacific daylight time, a Piper PA-24-250, N6744P, had a hard landing during an aborted takeoff at Mammoth Yosemite Airport (MMH), Mammoth Lakes, California. The owner/pilot was operating the airplane under the provisions of 14 CFR Part 91. The commercial pilot and one passenger were not injured; the airplane sustained substantial damage. The cross-country personal flight was departing MMH with a planned destination of San Diego, California. Visual meteorological conditions prevailed, and no flight plan had been filed. The approximate global positioning system (GPS) coordinates of the primary wreckage were 37 degrees 37.27 minutes north latitude and 118 degrees 50.15 minutes west longitude. The pilot stated in a written report that during his run-up he heard a loud squeal on the Unicom, but he then no further transmissions. He decided to depart MMH using runway 09. After he had made his radio transmission on the Unicom frequency stating his intentions to use runway 09, he heard no other radio transmissions. After takeoff, he kept the airplane in ground effect to gain airspeed. When he looked forward, he saw another airplane about 20 feet above the ground that he realized had just taken off using runway 27. The accident pilot aborted his takeoff, and on touchdown, he landed hard and the right main landing gear collapsed. The other airplane continued the takeoff without incident. The pilot stated that the airplane and engine had no mechanical failures or malfunctions during the flight.