On September 4, 1995, approximately 1205 hours Pacific daylight time, a Stinson 108-1, N8865K, sustained substantial damage when the right main landing gear collapsed during the landing roll on runway 17 at the Corvallis Municipal Airport, Corvallis, Oregon. The private pilot and two passengers were uninjured. Visual meteorological conditions existed and no flight had been filed. The flight, which was personal and local, was to have been operated under 14CFR91, and originated from Corvallis approxi- mately 15 minutes earlier. The pilot reported that he departed runway 17 at Corvallis and remained in the pattern with the intent of conducting a single touch-and-go landing on the same runway before departing the airport. He indicated that he flew a normal 70 mph approach and touched down on the "centerline on (the) 1000 foot square (runway fixed distance markings) (and) began (a) slight (10 degree) drift to l(eft)." He reported that the "plane responded poorly" and that the "plane lifted (the) left wing (or lowered the right wing) as (the) gear leg with (the) piston from (the) oleo lifted (the) right seat from (its) track" (refer to attached NTSB Form 6120.1/2). The pilot also reported in a separate NASA ASRS report that inspection of the runway revealed "rubber marks from (the) wheel up the runway suggesting that the right tire was scuffing and perhaps turned inward from at or very near (the) touchdown" (refer to photograph 1). Post crash examination revealed that the four retaining pins for the right main landing gear's shock strut retainer (cap) had sheared (refer to photograph 2). Gross examination of the pins revealed no evidence of fatigue. The pilot reported to an FAA inspector that he had purchased the aircraft one week previous to the accident and that a total of 14.3 hours had been logged in the previous year since the time the aircraft had been previously ground looped.