REPORTEDLY, THE ULTRALIGHT VEHICLE WAS ASSEMBLED AT AN ABANDONED ARPT, THEN WAS TEST FLOWN BY AN INTERNATIONAL ULTRALIGHT COMPANY SALESMAN. THE NON-RATED PLT, WHO WAS PLANNING TO BUY THE ULTRALIGHT, THEN FLEW THE VEHICLE TO FAMILIARIZE HIMSELF WITH ITS FLT CHARACTERISTICS. WITNESSES REPORTED THAT AFTER FLYING A SHORT TIME, THE PLT STARTED AN APCH TO LAND. WHEN THE ULTRALIGHT WAS ABOUT 50 TO 60 FT AGL, A WING FOLDED & THE VEHICLE CRASHED & BURNED. AN INVESTIGATION REVEALED THAT A STRUCTURAL CABLE HAD FAILED AT A SWEDGE FITTING. THERE WAS EVIDENCE OF NON-UNIFORM CRIMPING OF THE SWEDGE FITTING. TWO TYPES OF FRACTURES WERE FOUND WHERE THE CABLE FAILED (SHEAR & DUCTILE). THE SHEAR FAILURE WAS PREDOMINANTLY LOCATED AT THE SURFACE OF 1 BUNDLE OF WIRE STRANDS AT THE SWEDGE FITTING. THE DUCTILE FRACTURES WERE NOTED ON THE REMAINING INTERNAL STRANDS. THE PLASTIC FUEL TANK WAS INSTALLED ABOVE THE PLT. ON IMPACT, IT RUPTURED & SPILLED FUEL ON THE PLT & HOT ENG. THE PLT RECEIVED FATAL BURNS; ULTRALIGHT WAS CONSUMED BY FIRE.