Texarkana

While approaching for a landing, the aircraft pitched up, rolled inverted and impacted the terrain to the left of the runway. No preimpact part failure/malfunction was found; however, an investigation revealed the aircraft had been loaded with the center-of-gravity (cg) well behind the aft limit. The aircraft had been weighed on 9/8/84. Later, on 1/2/86, weight and balance data had been recomputed after removal of a radar and an autopilot, but an error had been made during the weight and balance preparation. Subsequently, the aircraft was operated in a tail heavy condition. Whether using the existing or the correct data, calculations for this flight should have shown the cg was behind the aft limit. The elevator trim tab was found trimmed to a full nose down position; 200 lbs of ballast had been installed in the vicinity of the aft cargo door. Tests of lung tissue showed the pilot and copilot had alcohol levels of 0,44‰ and 1,71‰, respectively. The pilot's urine tested 0,35‰ for alcohol. Also, phenyltoloxamine, acetaminophen and chlorpheniramine (medications commonly used in decongestants/antihistamines) were detected in his urine. Both occupants were killed.