On February 21, 1999, at 1100 central standard time (cst), a Cessna 182E, N3177Y, piloted by a commercial pilot, sustained substantial damage during taxi at East Troy Municipal Airport, in East Troy, Wisconsin, after a collapse of the right main landing gear. Visual meteorological conditions prevailed at the time of the accident. The commercial 14 CFR Part 91 flight was not operating on a flight plan. The pilot reported no injuries to himself or the four passengers. The flight was originating at the time of the accident. The pilot stated that after four parachutists had boarded the airplane, he began to taxi away from the gate. The pilot stated that the airplane traveled about 25 yards on the upward sloping grass terrain when the right main landing gear collapsed. Post accident investigation showed substantial damage to the right wing and horizontal stabilizer. Examination of the landing gear revealed a break approximately 10 inches from the inboard end of the landing gear leg at a point where it is clamped to the fuselage structure. Further examination of the airplane revealed no other anomalies. Examination of the landing gear by the Materials Laboratory Division of the National Transportation Safety Board indicated that the break stemmed from preexisting fatigue regions located on the lower forward surface of the landing gear leg. This area of the gear also contained evidence of fretting damage in areas where there had been a loss of paint.