On September 15, 1995, approximately 1315 hours mountain daylight time, a Cessna 180, N11JW, being flown by an airline transport pilot, was substantially damaged when the left main landing gear collapsed following a loss of control on landing roll on a paved road near Pray, Montana. The pilot and her husband were unin- jured. Visual meteorological conditions existed and no flight plan had been filed. The flight, which was personal, was to have been operated under 14CFR91, and originated from Nampa, Idaho, approximately 1030. The pilot reported that she lined up on the 6,000 foot long by 30 foot wide macadam road for landing headed approximately 150 degrees after receiving a radio call of calm winds and "touched down harder than normal and the tailwheel started to shimmy immediately." She reported that the aircraft began a right drift on rollout which she corrected with left rudder/tailwheel steering and that once back on the centerline she applied right rudder/tailwheel steering to track on the centerline but perceived no effect. The aircraft continued its left drift and the left wheel encountered an approximate three foot downslope area at the edge of the road and began sliding downhill. The pilot reported that "while the aircraft was sliding, it struck a rock causing the left gear to fold" (refer to attached NTSB Form 6120.1/2). The pilot reported that subsequent to the landing she observed a windsock indicating a right quartering crosswind of 10-15 knots from the north and that a pilot who landed immediately beforehand reported the winds as changing direction drastically. Post crash examination of the aircraft's tailwheel steering system by an FAA inspector revealed that the steering mechanism functioned normally for commanded left turns but that mechanical wearing and a bent compression spring prevented commanded right turns (refer to attachment).