On April 28, 2002, approximately 1300 mountain daylight time (MDT), a Cessna 177B, N34858, registered to and being flown by an airline transport pilot, sustained substantial damage when the right main landing gear collapsed on landing roll at the owner's personal landing site approximately two nautical miles southwest of New Plymouth, Idaho. The pilot and accompanying passenger were uninjured. Visual meteorological conditions prevailed and no flight plan had been filed. The flight, which was personal, was operated under 14 CFR 91 and had originated from McCall, Idaho, approximately 1200 MDT. According to Payette County Sheriff's Office report number 0202542, the responding deputy reported that the pilot was "...landing on his private landing strip..." when the accident occurred. He also reported that the tail of the aircraft was damaged as was the right wing and the right landing gear. He also reported that the aircraft's "...landing gear failed when he hit the ground...." The pilot indicated that he was landing to the south on the non-airspaced 1,300-foot long dirt strip, which he reported as being 100 feet wide. He further reported that he "...touched down in a patch of soft dirt..." and that the "...r[igh]t landing gear sunk in and rotated backwards...." The pilot also reported in the "Recommendation" section of his submitted NTSB Form 6120.1 (attached), "Soft dirt that had been compacted, should be checked for gopher holes, water leakage or condition more frequently."