On June 2, 1996, about 1312 eastern daylight time, a Shorts Brothers SD3-60, N826BE, registered to First National Bank Boston Trustee, operated by Gulfstream International Airlines, Inc., experienced loss of elevator trim shortly after takeoff from the Miami International Airport, Miami, Florida. Visual meteorological conditions prevailed at the time for flight 427A, a domestic, scheduled, passenger flight operated in accordance with 14 CFR Part 121. The airline transport-rated pilot and first officer, 1 flight attendant, and 32 passengers were not injured. The flight originated about 1311. The captain stated that the elevator trim worked fine during the preflight inspection and was set for takeoff. The first officer was flying the airplane and after takeoff while climbing through 300 feet, the elevator trim failed. An emergency was declared and he assisted the co-pilot with manipulation of the power levers. The flight returned and landed uneventfully. Examination of the elevator trim control cable system revealed a failed segment of the control cable from fuselage station 74 in the cockpit, to fuselage station 310 in the cabin. The cable failed about midpoint between a 45-degree change in direction and the cable controls nose-down trim. The cable segment has a total of three, 45-degree changes in direction and the elevator trim system is only manually controlled. Review of the airplane manufacturer maintenance program revealed that the elevator trim cables are required to be inspected every 4,800 hours or 1,460 days. Cable replacement is on condition. The elevator trim cables were last inspected on November 8, 1994, or 573 days earlier and the airplane had been operated for 1,679.4 hours and 2,017 cycles since. The operator of the airplane indicated that the cables have not been replaced since the airplane was manufactured and had accumulated a total time of 10, 953.0 hours and 16,193 cycles. The airplane was released to Mr. Wayne R. Modney, Director of Quality Control, on June 3, 1996. The retained cable was also released to him on May 8, 1997.