On July 28, 1994 at 0917 central daylight time, a Miller Skybolt, N919JM was substantially damaged following a loss of control during landing at Muscle Shoals, Alabama. The commercial pilot was not injured in the accident. The aircraft was operated by the pilot, under the provisions of 14 CFR Part 91. Visual meteorological conditions existed at the time, and no flight plan had been filed for the personal flight. The flight departed Mobile, Alabama at 0730, and was enroute to Oshkosh, Wisconsin. The pilot stated that left main landing gear strut failed during landing, and he lost control of the aircraft. The aircraft ground looped causing substantial damage to the left wing and left wing strut. Examination of the left main landing gear revealed that the left landing gear strut had fractured, and the left gear had collapsed. The pilot reported that the fracture surface was visually examined in bright sunlight. He noted a "...change in [the] crystal structure of the steel: a 3/8 to 1/2 inch radial area with a larger nodular appearance with respect to the homogenous fine gray granular appearance of the rest of the surface. The outher 1/32 inch of the different area was quite black. We, therefore, surmised the presence of a previously unknown radial crack in the member, perhaps a manufacturing defect, present all along."