On July 7, 2003, about 1735 Pacific daylight time, a Cessna 402 B, N98635, sustained substantial damage to the left wing assembly following a main gear collapse at the Lake County Airport, Lakeview, Oregon. The airplane is owned and operated by Ameriflight, Inc., Burbank, California, and was being operated as a domestic cargo flight under the provisions of Title 14, CFR 135, when the accident occurred. The airline transport pilot was the sole occupant of the airplane and was not injured. Visual meteorological conditions prevailed and a company flight plan had been activated. During a telephone conversation with the NTSB IIC on July 7, the pilot reported that the airplane's left main landing gear assembly collapsed while taxiing the airplane from the ramp to runway 16. FAA inspectors from the Hillsboro, Oregon, Flight Standards District Office (FSDO) and representatives from the operator examined the airplane's left main landing gear assembly following the accident. The examination revealed that the roll pin (part number NAS 561P4) that retains the attaching shaft (part number 0841011-1) to the trunnion assembly was fractured. This allowed the landing gear attaching shaft to shift from its installed position, resulting in the trunnion assembly separating from the landing gear support structure. Refer to the attached landing gear diagram for further information. Following the inspection of the failed landing gear, the operator inspected the landing gear of its remaining Cessna 402's, six in total. Subsequent to the inspections, the operator reported that they identified two aircraft with broken landing gear shaft roll pins. The roll pins were replaced, and the operator reported that the landing gear assemblies would be reexamined in six-month intervals.