On February 10, 2004, at 0950 Pacific standard time, a Lancair LC42-550FG, N6503C, registered to Columbia Aero LLC, operated by Lancair as a 14 CFR Part 91 business flight, veered off the runway during the landing roll at Roberts Field, Redmond, Oregon, and collided with a taxi sign. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft was substantially damaged and the commercial pilot, flight instructor and two passengers were not injured. The flight departed from Bend, Oregon, about 10 minutes prior to the accident. During a telephone interview and subsequent written statement from both the commercial pilot and flight instructor, it was reported that the commercial pilot was in the left seat and at the flight controls for the landing to runway 10. The commercial pilot stated that the approach was normal. When the aircraft was over the runway, about four feet above ground level, the stall warning horn sounded and he "chopped the power," and the aircraft rapidly descended to the runway. The aircraft touched down slightly left of runway centerline and in a nose high attitude. After the aircraft touched down the commercial pilot applied full power. The aircraft veered to the left, and at this time the flight instructor stated that he got on the rudder pedals and flight control in an attempt to regain runway heading. The flight instructor not realizing at first that the commercial pilot had applied full power, called for the commercial pilot to reduce power. Power was reduced, however, the aircraft exited the runway surface traveling over gravel and snow. During the landing roll, the right wing collided with a taxi sign, the outboard section of the right wing flap separated at the two outboard flap hinges, and the right main landing gear tire separated from the gear leg. Both pilots reported no mechanical failures or malfunctions with the aircraft at the time of the accident.