On July 26, 2015, about 0830 mountain daylight time, a Cessna 180J, N52095, sustained substantial damage while taxiing for takeoff following a reported loss of the right brake control at the Wilson Bar USFS Airport (C48) Dixie, Idaho. The airplane was registered to a private individual and operated by SP Aircraft under the provisions of Title 14 Code of Federal Regulations Part 135. The commercial pilot and three passengers were not injured. Visual meteorological conditions prevailed and no flight plan was filed for the non-scheduled passenger flight. The flight was originating at the time with a planned destination of Boise Air Terminal/Gowen Field, Boise, Idaho. The pilot reported that the right brake failed while performing a 180 degree turn to align the airplane with the runway. As a result, the pilot stated that he intentionally ground looped the airplane, in order to avoid elevated terrain near the runway. Subsequently, the right wing struck terrain. Postaccident examination of the damaged airplane by a Federal Aviation Administration inspector revealed that substantial damage was sustained to the right wing and aileron. The right brake hydraulic line was observed to be cracked at a bend between the fuselage and the main landing gear leg. The airplane is equipped with a hydraulically actuated disc brake on each wheel. Each brake is connected by a hydraulic line to a master cylinder attached to each side of the pilot's rudder pedals. The appropriate section of the brake hydraulic line was removed and sent to the National Transportation Safety Board, Materials Laboratory Division, for a detailed examination. Electron microscope images revealed that the brake line fracture surface was consistent with a fatigue fracture. Fatigue striations and ratchet mark formations were observed.