On July 16, 2003, about 0740 Pacific daylight time, a Beech F90 King Air, N299KP, sustained substantial damage when it collided with terrain, following a runway overrun while landing at the Sunriver Airport, Sunriver, Oregon. The Airplane is owned by King Air Partners, LLC, and was being operated as a cross-country flight under the provisions of Title 14, CFR Part 91, when the accident occurred. The airline transport pilot-in-command, was not injured. Visual meteorological conditions prevailed for the flight that was being operated on an instrument flight rules flight plan. The flight originated from Sacramento, California, (KMMC) about 0620. During a telephone conversation with the National Transportation Safety Board investigator-in-charge on July 16, the pilot reported that while landing on runway 18, he inadvertently touched down approximately halfway down the 5,455 foot long, asphalt covered runway. The pilot said that after the initial touchdown, he applied maximum braking and full reverse power. The airplane continued off the end off the runway, eventually coming to rest approximately 35 feet beyond the runway threshold. During the overrun, the airplane's right main gear collapsed, and the right wing struck the ground. In a subsequent written report dated July 22, the pilot reported that the aircraft's right main wheel brake locked up during the landing roll. He also reported that he was landing with a tailwind. Runway 18 is serviced by a 2-box, 3 degree VASI.