On July 5, 1998, at approximately 0800 central daylight time, a Cessna T188C agricultural airplane, N3963J, was substantially damaged, upon collision with terrain during initial takeoff climb, near Weslaco, Texas. The foreign private pilot was not injured. The airplane was owned and operated by a private individual in Buenos Aires, Argentina. The airplane was being ferried to Buenos Aires, Argentina, under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the cross country flight for which a VFR flight plan was filed. The flight was originating at the time of the accident. According to the pilot, the airplane was purchased by an Argentine airplane broker from an operator in Stinnett, Texas. The airplane was subsequently ferried to Lubbock, Texas, where a ferry kit was installed to enable the airplane to carry fuel in the hopper for the ferry flight to Argentina, South America. The airplane landed at the Weslaco Mid Valley Airport on the previous afternoon on the first overnight stop of the flight to South America. The airplane was topped off for the next day's scheduled flight to Tegucigalpa, Honduras. A witness observed a similar airplane depart two minutes ahead of the accident airplane. She noticed that "the heavily loaded" airplane broke ground fairly quick and "established a good rate of climb after takeoff." The same witness observed the accident airplane takeoff and initiate a climb. The witness stated that she "immediately noted a marked decrease in performance" in the second airplane. The witness further stated that the "airplane failed to gain altitude after a rather long takeoff roll." The 375 hours Argentine private pilot attempted to land straight ahead in a rough and uneven field. The pilot reported that the airplane landed hard and both main landing gears were torn off upon initial ground impact. The airplane came to rest in the upright position. Examination of the wreckage by the FAA inspector revealed that the landing gear attaching points sustained structural damaged. The engine firewall was bent, and the forward portion of the underside of the fuselage also sustained structural damage. The fuel on board was found to be free of contaminants. The pilot told the FAA inspector that the engine "did not appear to be producing full power" and he suspected that either the turbocharger failed, or the propeller was not in low pitch/high rpm setting. The reason for the loss of engine power could not be determined. The FAA inspector provided the pilot an NTSB Form 6120.1/2 to be completed prior to his departure from the United Sates. The pilot departed for Argentina without completing the form.