On October 5, 1996, approximately 1500 central daylight time, a Hispano Aviacion (Casa) HA-200 Saeta, N3179K, registered to and operated by a private owner, as a Title 14 CFR Part 91 personal flight, was substantially damaged during a precautionary landing near Elk City, Oklahoma. Visual meteorological conditions prevailed, and a flight plan was not filed. The commercial pilot and passenger were not injured. The flight originated from Wichita, Kansas, about 1 hour before the accident. The pilot reported to the investigator-in-charge the following information. While in cruise flight the airplane experienced a fuel feed problem from the left wing tip fuel tank to the rear fuselage fuel tank. The pilot made the decision to execute a precautionary landing at the Elk City Municipal Airport to correct the fuel imbalance problem. While on short final to runway 17, at approximately 100 feet AGL, the pilot attempted to jettison the fuel from both wing tip fuel tanks in order to maintain aircraft control. The jettison cap opened fully on the right wing tip tank; however, the jettison cap on the left wing tip tank only opened partially. The pilot applied full right aileron and rudder; however, the airplane's left wing tip "hit" the grass to the left of the runway. During the landing roll, the airplane veered off the runway to the left, crossed a drainage ditch, and came to rest upright approximately 650 feet from the runway. An examination of the airplane by the FAA inspector revealed that the nose and main landing gear had collapsed, the top of the right wing near the fuselage was wrinkled, and the left wing tip fuel tank had separated from the wing. An examination of the airplane's wing tip fuel tanks by the NTSB revealed that the right tip tank was intact and undamaged with the fuel dump cap missing. The left tip tank was split in half along a rivet line near the mid point of the tank, and the fuel dump cap was missing. The dump cable release was binding, and initially pulling on the cable did not retract the one ball bearing found protruding from the cylinder wall. After pulling the cable about 10 times it freed up and began to retract the ball bearing. The portion of the dump mechanism that remains with the tank appeared to be permanently attached to the inside of the tank and was not identical to the inner piece found in the right tip tank. See the enclosed photos.