On July 6, 2008, approximately 1215 mountain daylight time, a Lancair Company LC41-550FG (Columbia 400), N2544W, sustained substantial damage when it impacted a pole and fence while taxiing out for takeoff at Friedman Memorial Airport (SUN), Hailey, Idaho. The commercial pilot and his passenger were not injured. The pilot/owner was operating the airplane under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed for the personal cross-country flight, which was originating at the time of the accident. A flight plan had not been filed. The pilot reported that when taxiing this airplane, differential braking is used for directional control, and that while taxiing for departure, the right brake failed. Subsequently, the airplane departed the left side of the taxiway, impacted a pole and went down an embankment, striking an airport perimeter fence. The left composite wing tip was split open and the wing's leading edge had an 8- to 10-inch chordwise rip in it. Postaccident examination of the airplane by a Federal Aviation Administration inspector found the right brake O-ring in the piston that operates the caliper to be hard and flat. When brake fluid was put in the system and the brakes were pumped, the brake fluid was observed to pass directly through the right-hand caliper onto the ground.