On July 6, 2005, about 1800 Alaska daylight time, N333TB, a tailwheel-equipped Helio H-250 airplane, sustained substantial damage during the landing roll at the Merrill Field Airport, Anchorage, Alaska. The airplane was being operated as a visual flight rules (VFR) local area instructional flight under Title 14, CFR Part 91, when the accident occurred. The first pilot, a certificated flight instructor seated in the right seat, and the second pilot, a private pilot seated in the left seat, were not injured. The second pilot owned the accident airplane. Visual meteorological conditions prevailed, and no flight plan was filed. The flight originated at the Merrill Field Airport, about 1700. During an on scene conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on July 6, the first pilot reported that he was providing flight instruction/recurrent training to the second pilot. The first pilot said that after an uneventful touchdown on the dry and paved asphalt of runway 24, a loud shuddering noise was heard as the second pilot applied the brakes. As they continued the landing roll, the right main landing gear collapsed, and the right wing struck the runway. The airplane sustained structural damage to the right wing. A postaccident inspection revealed that the right main landing gear leg assembly had fractured about 6 inches from the fuselage attach point. According to the airplane owner, the fractured main landing gear leg assembly, part number 250-040-451-1, had accumulated about 7,006 hours in service. The main landing gear leg assembly is constructed of 1/8-inch steel, which is molded and welding to form a 2-inch square steel tube. The main landing gear leg is covered by a contoured fairing assembly that conceals the area that fractured on the accident airplane. A visual inspection of the fractured right main landing gear leg assembly in the fracture zone area, revealed brownish rust-colored deposits that covered about 1/4 of the circumference of the main landing gear tube. The remaining 3/4 circumference of the main landing gear tube had a 45-degree sheer lip.