On November 24, 1998, at 1600 central standard time, a Stanton Staros SA 260 amateur-built experimental aerobatic airplane, N540HC, was destroyed when it impacted terrain after the pilot executed an emergency bailout due to an in-flight fire near Marion, Texas. The airplane was registered to HC & NR, Inc. of Seguin Texas, and operated by a private individual. The non-instrument rated commercial pilot, sole occupant of the airplane, sustained serious injuries. Visual meteorological conditions prevailed and no flight plan was filed for the 14 Code of Federal Regulations (CFR) Part 91 aerobatic flight. The local flight originated from the Zuehl Airport, Marion, Texas, at 1545. The 980-hour pilot reported in the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2) that he performed a pre-flight examination and confirmed that the "gas cap was secure." He departed from the Zuehl Airport and flew the airplane to a nearby aerobatic box and flew the "proposed 1999 advanced known sequence." The pilot initiated the same sequence a second time. The pilot stated that he was executing "a half outside loop push from inverted, with a full roll followed by a snap roll in horizontal flight at the completion of the half loop" and was approaching a near vertical attitude when he was "splashed with a very significant amount of [fuel]." The fuel appeared to come from below the instrument panel. The pilot leveled the airplane, and as he was reaching to turn the fuel shut off valve to the OFF position, "something ignited the fuel vapors," and a fire erupted. The pilot reported that he "suspects that a fuel line between the main tank and the header tank," separated. He was not able to reach the fuel shut-off valve and maneuvered the airplane into a "vertical down line and jettisoned the canopy." The pilot exited the airplane approximately 400 feet agl, and his parachute opened at tree top level. The airplane impacted terrain nose first, in a near vertical pitch attitude. The airplane came to rest inverted on a measured magnetic heading of 180 degrees. The pilot landed 100 feet northwest of the wreckage. A witness reported that the airplane was at 2,500 feet when he heard a "loud pop." He observed the airplane descending and the pilot's parachute deploy at 250 feet AGL. He also stated that flames were in the area of the engine cowling. Another witness reported that the airplane was approximately 3,000 feet and "at the top of a vertical climb" when he heard a "loud pop." The airplane then entered a level pitch attitude followed by a descent. He reported that the pilot's parachute deployed at 300 feet agl, and the airplane impacted the ground. An FAA inspector examined the airplane and reported that a fire consumed the entire fabric covered airplane, including the fuel system. He added that the parachute and pilot's apparel, including sunglasses, gloves, and headset were charred and melted. The right wing structure separated from the airplane, and the right aileron separated from the wing. The fuel line between the main fuel tank and the header tank was destroyed during the fire. The fuel filler neck was located at the accident site and exhibited crushing damage and bending deformation. The main fuel cap was not recovered. The airplane was equipped with a main fuel tank and a header tank. The header tank was positioned forward of the instrument panel, between the pilot's legs, within the cockpit area. The main fuel tank was situated above the header tank. The main fuel filler cap (stopper type) is located in the cockpit area and accessed through a door in the upper cowling. The fuel filler neck was examined at the NTSB Materials Laboratory located in Washington, D.C. The neck and fillet weld around the base of the neck exhibited crushing damage and bending deformation. Weld fractures on the neck contained mechanical and fire damage in addition to "ductile dimple features typical of overstress separation." A review of the aircraft logbooks did not reveal evidence of any maintenance to the fuel system or uncorrected maintenance defects.