On March 8, 2003, at 1027 eastern standard time, a Fokker F-27MK 500, N712FE, registered to Federal Express Corporation and operated by Mountain Air Cargo Incorporated, right main landing gear collapse during an emergency landing at Kinston Regional Jetport, Kinston, North Carolina. The cargo flight was operated under the provision of Title 14 Part 121. Visual meteorological conditions prevailed at the time of the accident with an instrument flight plan filed. The airplane sustained substantial damage and the pilot and co-pilot were not injured. The flight departed Piedmont Triad International Airport, Greensboro, North Carolina, at 0816 on March 8, 2003. . According to the pilot, an unsafe right gear indication was received during approach to Craven County Regional, New Bern, North Carolina. During a flyby the control tower controller confirmed the right gear was not fully extended. The pilot declared an emergency and diverted to Kinston Regional Jetport to conduct an emergency landing on runway 05. On landing roll the right main landing gear collapsed and the airplane slid off of the runway. Examination of the right main landing gear revealed the drag brace was fractured. Examination of the drag stay tube revealed, the tube was fractured approximately 15.5 inches below the attachment clevis at the upper end. The fracture was located at the lower side of a transition from a smaller internal diameter on the upper piece to a larger internal diameter on the lower piece. The region of the fracture surface was flat and perpendicular to the tube longitudinal axis. The region had a smooth, curving boundary, also consistent with fatigue. The fatigue features emanated from multiple origins at the inner surface of the tube. The remainder of the fracture was matte gray and on slant angles, features consistent with overstress fracture. The mating fracture features on the upper piece were similar. The Federal Aviation Administration (FAA) issued an Airworthiness Directive (AD) requiring an inspections of main landing gear drag stay units. The AD was prompted by the fracture of a drag stay tube from fatigue cracking that initiated from an improperly machined transition radius at the inner surface of the tube. According to Fokker ,the Fokker F27 Mark 500 airplanes (such as the incident airplane) were not equipped with drag stay units having part number 200261001, 200485001, or 200684001. One tube, part number 200259300, had a change in internal diameter (stepped bore), and the other tube, part number 200485300, had a straight internal bore. AD 97-04-08 required an ultrasonic inspection to determine if the installed tube had a straight or stepped bore. A review of maintenance records revealed that the failed drag stay tube had accumulated 28, 285 total cycles.