On October 10, 2003 about 1400 Alaska daylight time, a wheel-equipped Cessna 180 airplane, N9278C, sustained substantial damage when the left main landing gear wheel separated from the airplane during landing at a private airstrip, about 15 miles east of McCarthy, Alaska. The airplane was being operated by the pilot as a visual flight rules (VFR) personal flight under Title 14, CFR Part 91, when the accident occurred. The solo commercial pilot was not injured. Visual meteorological conditions prevailed, and no flight plan was filed. The flight originated at the McCarthy Airport, McCarthy, about 1330. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on October 10, a friend of the pilot said he was relaying information received from the pilot via radio telephone. He related the pilot said he was ferrying supplies to a remote airstrip located on a family homestead. The pilot said on about the tenth trip to the homestead, the left main landing gear wheel separated from the airplane during landing, resulting in the collapse of the right main landing gear, and structural damage to the right wing and the fuselage. During a telephone conversation with the NTSB IIC on October 14, the pilot said the day prior to the accident the airplane's landing gear was changed from floats to wheels. He said there were no mechanical or installation problems noted during the exchange. The pilot said he had made about 10 trips with supplies from McCarthy, about 15 miles from the homestead, prior to the accident. He said the runway is one-way in, and he landed with a slight tailwind. In a subsequent written statement by the pilot dated November 18, the pilot reported a smooth approach and touchdown. After the wheels made contact with the ground he reported that the "left landing gear snapped off along the top two axle mounting bolts," and that the left gear leg furrowing into the ground resulted in the airplane veering sharply to the left. The right main landing gear collapsed, and the fuselage and right wing impacted the ground.