On July 9, 1996, about 1605 Atlantic Standard Time, a Short Brothers SD3-60-200, N384MQ, operated by Executive Airlines, Inc., dba American Eagle as flight No. 5514, experienced failure of a segment of the elevator trim cable system during the initial climb after takeoff at the Luis Munoz Marin International Airport, San Juan, Puerto Rico. Visual meteorological conditions prevailed at the time and an IFR flight plan was filed for the scheduled, domestic, passenger flight operated in accordance with 14 CFR Part 121. The airplane was not damaged and the airline transport-rated pilot and first officer, 1 flight attendant, and 9 passengers were not injured. The flight originated about 5 minutes earlier. The first officer who was flying the airplane stated that after flap retraction while retrimming the airplane to a nose-up attitude, he felt no resistance from the manual elevator trim wheel. The flight then returned and landed uneventfully. Examination of the elevator trim control system revealed a failed cable segment between fuselage station 74 in the cockpit and fuselage station 310 in the cabin area. The cable failed about midpoint between a 45-degree change in direction and was for nose-up trim. The failed cable was removed for further examination. Metallurgical examination of the failed cable revealed that 36 of the 49 individual wire strands failed due to fatigue. Additionally, wear was noted adjacent to the fatigue failed strands. The remaining strands failed due to overload. The airplane manufacturer requires the elevator trim control system to be inspected every 4,800 hours of 4 years, but replacement is on condition. The airplane operator introduced an engineering change order to the fleet which required inspection every 2,400 hours. Review of the airplane maintenance records revealed that the trim control system was last inspected 2,247.5 hours and 3,969 cycles earlier at the time of the failure. The airplane was released to Mr. Ramon Ruiz, Director of Quality Assurance on July 11, 1996. The retained cable was released to Mr. Luiz Ruiz, Stores Regional Manager, on May 12, 1997.