On October 27, 1999, approximately 1800 mountain daylight time, a Cessna 172M, N12376, experienced a gear collapse after running off the end of the runway during a precautionary landing at Star "S" Ranch, Mackay, Idaho. The private pilot and his passenger were not injured, but the aircraft, which was owned and operated by Sandpoint Aviation Services, sustained substantial damage. The 14 CFR Part 91 personal pleasure flight, which departed Sandpoint about three hours and 15 minutes prior to the accident, was being operated in visual meteorological conditions. The aircraft had been on a VFR flight plan, and there was no report of an ELT activation. According to the pilot, while en route, he deviated to avoid mountain obscuration due to smoke and haze. Upon resuming his original course, he encountered a headwind that was greater than he had flight planned for. Because of the deviation and the wind conditions, it appeared to the pilot that he did not have enough fuel to make it to his intended destination. He therefore decided to make a precautionary landing at the Star "S" Ranch airstrip. As he approached the Star "S" strip, he kept his altitude higher than normal because of the rapidly rising terrain surrounding the landing area. He then descended steeper than normal on base and final, and crossed the threshold at about 75 knots indicated airspeed. He reported that the aircraft floated before touching down at least one-quarter way down the 5,000 foot long grass airstrip. After touchdown and before he had applied the brakes, a wind gust lifted the aircraft back into the air. After touching down a second time, the pilot applied maximum breaking, but was unable to stop the aircraft before it ran off the end of the runway and dropped over a 20 foot high embankment onto rough/uneven terrain. During the rollout on the terrain at the bottom of the embankment, the nose wheel and the right main gear collapsed, resulting in substantial damage to the aircraft. According to the pilot, there was no evidence of engine, control system, or brake system malfunction.