On August 12, 1993, at approximately 1000 hours mountain daylight time (MDT), a Cessna 185C, N2690Z, registered to and being operated/flown by Guy A. Pere, an airline transport rated pilot doing business as Pere Air, sustained substantial damage during a loss of control while landing at the Pistol Creek private airstrip near Stibnite, Idaho. The pilot reported that he and his two passengers were uninjured and that visual meteorological conditions prevailed at the time of the mishap. A company flight plan was in effect. The flight, which was an unscheduled passenger flight, was to have been operated in accordance with the requirements set forth in 14CFR135 and originated from the Friedman Memorial Airport, Hailey, Idaho, at approximately 0900 hours. The pilot reported that during the landing rollout he lost the left brake and the aircraft ground looped 180 degrees impacting the left wing. Post crash examination of the aircraft by FAA Inspector Russell Graves revealed brake fluid inside the fuselage where the left brake line passes from outside to inside the fuselage. There was no other evidence of fluid leakage associated with the brake system. Additionally, Inspector Graves reported that all "B-nuts" were found to be tight with the exception of "the outside nut that is attached to the bulkhead fitting that goes through the fuselage (and) was loosened easily with a wrench." No mechanical defects were found during the examination of the brake system and the left brake master cylinder contained only a small amount of fluid" (refer to attached statement of Russell E. Graves). The aircraft airframe log contained an entry dated 08/11/93 which read in part "Replaced L/H outboard landing gear support bracket with new unit from P. Ponk Aviation, P/N PPA 1301-1. See 337 Form. Removed cargo pack, revised W & B and equipment list." The entry was signed off by Tim W. Charles, A & P 519886010. Pilot Pere reported to the Investigator in Charge during a telephonic conversation that he assisted the mechanic in the maintenance work accomplished on 08/11/93, including the tightening of the left brake lines inside the fuselage. He stated that he did not recall tightening the B-nut and was uncertain as to whether the mechanic inspected the work he accomplished.