CHURCHTOWN, OH, USA
N49YP
UPTON MUSTANG II
THE AIRPLANE WAS OBSERVED ENTERING AN AEROBATIC MANEUVER SIMILAR TO A TAIL SLIDE. DURING THE MANEUVERING, AN IN-FLIGHT BREAKUP OF THE AIRPLANE OCCURRED. PIECES OF THE AIRPLANE WERE FOUND OVER AN 1800' AREA. AN EXAM OF THE WRECKAGE REVEALED THAT THE CANOPY HAD SHATTERED; THE RIGHT HORIZONTAL STABILIZER, RIGHT ELEVATOR, LEFT AILERON, CANOPY FRAME & PASSENGER'S BODY HAD SEPARATED FROM THE MAIN WRECKAGE. THERE WAS EVIDENCE OF DOWNWARD DEFORMATION ON THE SEPARATED STABILIZER & ELEVATOR. ALSO, EVIDENCE OF A PREEXISTING CRACK WAS FOUND IN THE CANOPY LATCH MECHANISM, BUT THE INVESTIGATION DID NOT DETERMINE WHETHER THE LATCH HAD FAILED BEFORE OR AFTER THE IN-FLIGHT BREAKUP HAD BEGUN. THE AIRPLANE KIT MANUFACTURER DISCOURAGED TAIL SLIDES.
HISTORY OF FLIGHT On June 14, 1994, about 1528 hours eastern daylight time, N49YP, an Upton Mustang II home built airplane, operated by the owner/pilot, impacted terrain during an uncontrolled descent and was destroyed in Churchtown, Ohio. The descent was precipitated by a structural failure and loss of control while maneuvering. The pilot and his passenger were fatally injured. Visual meteorological conditions prevailed and a flight plan was not filed. The local flight originated from Parkersburg, West Virginia, at 1520 and was conducted under 14 CFR 91. According to witness statements, the purpose of the flight was to provide a "short airplane ride" for the passenger. The passenger was introduced to the pilot through an acquaintance of the pilot. The acquaintance and his co-worker were with the pilot and passenger just prior to the flight. No indication of aircraft problems or pilot ailments were noted by the acquaintance or his co-worker. The acquaintance stated that he saw the airplane taxi out and takeoff. He stated that the takeoff was "very smooth" with no perceived problems. He also stated that the canopy was closed during the takeoff and that the airplane was headed toward the "west practice area." The acquaintance and his co-worker both stated that they were not under the impression that the flight would include aerobatic maneuvers. According to FAA Air Traffic Control Tower personnel at the Wood County Airport in Parkersburg, the pilot contacted that tower and stated that he would be on a "local VFR flight." The pilot was cleared for takeoff at 1520 and approved for a "straight out departure" to the west. There were no further recorded transmissions or distress calls from the pilot. About 1530, a witness located about 1/2 mile from the accident site stated that he heard an airplane overhead, causing him to look up. The airplane was "at a fairly high altitude" and in a "complete vertical climb going straight up." He then stated that the engine "quit" and the airplane "starting coming tail first down." The witness stated that he then heard the engine being "restarted." He heard it "backfiring like an automobile" and "running rough like it wasn't getting enough fuel." During this time, it appeared to the witness that the airplane was beginning to "level out" because the "front end came forward a bit;" however, the airplane continued to fall "tail first." The witness then heard a "loud cracking sound" like "somebody cracked a whip - then dead silence." The airplane was then observed to descend tail first until it disappeared behind trees. Another ground witness, located about 1 mile from the accident site, stated that he heard the airplane "circling" for about 1 to 2 minutes. He further stated that it "sounded like it was real low." He then heard the engine "spurting." Five other ground witnesses who were in the vicinity of the accident site stated that they first saw the airplane as it was descending toward the ground. Four of the witnesses stated that they heard an "explosion" and saw debris fall from the airplane as the airplane was descending from 300 feet to 50 feet above the ground immediately prior to ground impact. One of the ground witnesses was located about 100 feet from the accident site. She stated: I had walked out into my front yard along [State Highway] 676 and I heard an explosion. I looked up and ... saw something falling from the plane. It looked to me like it was round and black and it fell down to the ground. I did not see any smoke or fire when the plane was in the air. The plane was dropping down fast, real fast and in just a few seconds.... The plane hit the road and stopped where it was. PERSONNEL INFORMATION According to FAA records, the pilot, age 63, was a certificated commercial pilot with ratings for instrument, single and multiengine land airplanes. The pilot was issued an FAA Second Class Medical Certificate on June 17, 1993, with the limitation that he "must wear corrective lenses." An examination of the pilot's logbook indicated that he had logged about 3,800 hours of total flight time, including 25 hours in type during the 90 days prior to the date of the accident. According to acquaintances of the pilot, and published statements by the pilot in aviation publications, the pilot had performed aerobatics maneuvers, including tail slides, with the accident airplane during numerous airshows from May 1987 until 1993. According to witness statements, the pilot had stated that he stopped performing in airshows because "it was too much stress" on the airplane. AIRCRAFT INFORMATION The accident airplane was an all-metal, low-wing, two-seat, airplane with an empty weight of 1,100 pounds. The airplane was equipped with a 160-horsepower Lycoming O-320 engine and a Hartzell constant speed propeller. According to Mustang Aeronautics, Inc., the kit manufacturer, there are about 300 Mustang II airplanes currently flying, with over 1,600 plan sets sold. The accident airplane was home built by Samuel Upton, Sarasota, Florida, and received an FAA Experimental Certificate on September 22, 1980. It was subsequently purchased and registered by the accident pilot on July 1, 1985. An examination of the airplane's engine and airframe logbooks revealed that the airplane had accumulated about 1,752 flight hours since it was built. The examination did not reveal any unresolved discrepancies prior to the accident flight. WRECKAGE AND IMPACT INFORMATION The airplane wreckage was examined by FAA aviation safety inspectors from Columbus, Ohio, at the accident site on the day of the accident, June 14, 1994, and again on June 15, 1994. Additional examinations by the Safety Board occurred on June 28, 1994, and January 25, 1995, after the wreckage had been moved. According to the FAA inspectors, the fuselage, cabin area and engine of the airplane came to rest in a nose-down attitude on the pavement of State Highway 676. The pavement underneath the nose of the airplane was pushed downward and forward about 1 foot. No evidence of fire was found. Pieces of canopy Plexiglas, the left wing root fairing, right horizontal stabilizer, right elevator, left aileron, passenger's body, and canopy frame, were found separated from the airplane and distributed, in that order, along a 1800-foot path oriented along a magnetic bearing of about 220 degrees. About 1,800 feet from the fuselage, a grassy area measuring about 30 feet by 100 feet was found covered by hundreds of small Plexiglas pieces. Each piece was about 2 inches in diameter. About 100 feet beyond this area, a strip of aluminum measuring 40 inches by 4 inches was found. The strip was identified as the left wing root fairing. The right horizontal stabilizer was found about 800 feet from the Plexiglas pieces. The right elevator was found about 100 feet beyond the right horizontal stabilizer. The left aileron and counterweight were found in a tree about 1,200 feet from the Plexiglas pieces. The canopy frame and passenger were found about 1,500 feet from the Plexiglas pieces. A portion of the trailing edge spar from the right horizontal stabilizer was found between the canopy frame and the fuselage of the airplane. A determination of pre-impact flight control continuity and operation was made impossible due to impact damage and in-flight structural failure. An examination of the separated right horizontal stabilizer trailing edge spar revealed that it was bent downward and separated at both ends. The mating surface found on the empennage of the airplane revealed an area of attachment screw holes in which the threads and surrounding material were crimped in downward bending. The separated right elevator was bent downward about 30 degrees beginning at a point about 12 inches from its tip. The hinge had separated from the elevator, and the hinge fitting that remained was bent aft and to the right. The elevator's control torque tube had separated at the center weld attach point on the control tube fitting located inside the airplane's empennage. The tube was bent downward slightly beginning about 4 inches from the weld. The trim tab was still attached to the elevator via its hinge. The trim tab actuator remained attached to the elevator, but was separated from the trim tab surface. The top surface of the aft edge of the elevator, located directly above the trim tab leading edge, was bent upward about 80 degrees. Two marks were found on the bottom surface of the trim tab. The distance between these two marks and the elevator root were the same as the distance from the elevator root and two protrusions from the tail wheel spring assembly, which is mounted on the very aft end of the airplane's underside. Blood was found on a broken piece of Plexiglas attached to the left side of the canopy frame. A specimen was removed from the canopy and analyzed by the Ohio State Police Crime Laboratory. The report of laboratory "... revealed the presence of human blood." A portion of the canopy latch mechanism (central hub) was found attached to the front of the canopy and fractured. The mating piece of the fracture was not recovered. The latch mechanism was removed from the canopy and analyzed by the Safety Board's Metallurgical Laboratory. According to the Metallurgist's Factual Report (attached): Visual examination of the fracture surface ... revealed a faint elliptical region adjacent to the cylindrical portion of the hub.... The fracture surface within this region had a slightly darker and smoother appearance than the remainder of the fracture. Scanning electron microscope (SEM) inspections of the fracture after disassembly and cleaning also indicated that the elliptical region had a faceted, relatively smooth and flat fracture topography that showed no indications of plasticity or fatigue striations.... The remainder of the fracture had a topography showing a mixture of flat facts and elongated dimples typical of an overstress separation.... The fracture surface was also interspersed with spherical pores typical of gas porosity. The report also stated the hub was "most probably a zinc die casting." Zinc alloys have relatively low strengths (41,000 per square inch ultimate typical) compared with other alloys used in critical aviation applications. A visual examination of the attach fitting on the canopy frame did not reveal evidence of bending, gouging, cracking, or tearing. The pilot was found completely strapped into the left seat at the accident site. The passenger had separated earlier from the airplane and was found about 240 feet from the right seat, which remained attached to the airplane. An examination of the right seat restraint system revealed that all buckles and latches were secured; however, the stitching of the seat belts had been pulled apart. The engine, a Lycoming model O-320-D1D, and propeller were examined. The engine block was shattered into several pieces. The propeller remained attached to the crankshaft. The two-blade Hartzell metal propeller was examined. One blade exhibited evidence of chordwise scratching and leading edge gouging along its entire length. The same blade also exhibited two distinct "S" bends. The other blade did not exhibit evidence of chordwise scratching or "S" bending. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed on the pilot and the passenger by Dr. Larry R. Tate, M.D., of the Franklin County Coroner's Office, Columbus, Ohio, on June 15, 1994. According to the Franklin County Coroner's toxicological report, the pilot had "71 % carbon monoxide" in his blood, and the passenger had "43 % carbon monoxide" in his blood. Additional testing of the specimens was performed by the Armed Forces Institute of Pathology, Washington, D.C. According to the report of toxicological examination on the pilot (attached): The carboxyhemoglobin saturation in the lung fluid was 7% as determined by gas chromatography with a limit of quantification of 1%. Carboxyhemoglobin saturation of 0-3% are expected for non-smokers and 3-10% for smokers. Saturations about 10% are considered elevated. According to the report of toxicological examination on the passenger (attached): "The carboxyhemoglobin saturation in the spleen was 6% as determined by gas chromatography with a limit of quantification of 1%." ADDITIONAL INFORMATION Aerobatic Limitations. According to performance specifications published by Mustang Aeronautics, Inc., the Mustang II has a top speed of 205 miles per hour (mph) and a cruise speed of 195 mph at 75 percent power at 8,000 feet. The airplane's design is "fully aerobatic to 6-G's positive and negative" when "operated at a weight of 1,250 pounds." The estimated weight of the accident airplane at the time of the accident was about 1,500 pounds. Airplane Performance Capability. According to the President of Mustang Aeronautics, Inc.: "Speeds [in the Mustang II] will approach redline very quickly if the power is not reduced. "G" loads can build up dramatically during a pull up from a high speed dive, ... . A Mustang can exceed the redline without power." The company also discourages pilots from performing tail slides in the Mustang II. Recent Accident History. According to Safety Board records, the Mustang II was involved in three accidents from December 5, 1993 to June 14, 1994, in which evidence of in-flight catastrophic structural failure was found. Two of the accidents had two occupants on board and were observed by witnesses performing aerobatics maneuvers. Both airplanes from these two accidents were built by the same professional builder. At the time of this factual report, the probable cause has not yet been issued by the Safety Board for these two accidents. The other Mustang II accident had one occupant on board. The probable cause cited by the Safety Board was: "The in flight failure of the left aileron for reasons undetermined."
THE PILOT'S PERFORMANCE OF A MANEUVER THAT EXCEEDED THE DESIGN STRESS LIMITS OF THE AIRPLANE.
Source: NTSB Aviation Accident Database
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