WEST JORDON, UT, USA
N31WD
GLINES ACRO DUSTER II SA750
GROUND WITNESSES OBSERVED THE AIRPLANE PERFORMING AEROBATICS, INCLUDING ROLLS, SEVERAL MINUTES PRIOR TO THE ACCIDENT. IMMEDIATELY PRIOR TO THE ACCIDENT, WITNESSES DESCRIBED THAT THE AIRPLANE 'ROLLED' ABOUT 500 FEET ABOVE THE GROUND. DURING THE ROLL, THE ENGINE POWER DECREASED. THE AIRPLANE AERODYNAMICALLY STALLED AND DESCENDED INTO THE GROUND. AN EXAMINATION OF THE WRECKAGE, INCLUDING THE ENGINE, DID NOT DISCLOSE ANY EVIDENCE OF PRE-IMPACT MECHANICAL MALFUNCTION.
HISTORY OF FLIGHT On October 8, 1994, about 1320 hours mountain daylight time, N31WD, a Glines Acro Duster II SA750 home built airplane, operated by the owner/pilot, collided with terrain while maneuvering and was destroyed in West Jordon, Utah. The private pilot and his passenger were fatally injured. Visual meteorological conditions prevailed and no flight plan had been filed. The personal flight departed from Salt Lake City Airport No. 2, Utah, and was conducted under 14 CFR 91. According to witnesses and fueling records, the airplane's 25-gallon main fuel tank was "topped off" with 11.9 gallons of 100 low lead aviation fuel on October 7, 1994. The airplane was then flown for about 1/2 hour with no reported problems. On the following day, the airplane was flown for about 25 minutes, again with no reported problems. Later during the day, the pilot decided to fly one more time. The pilot offered the son of a friend a ride in the airplane. According to witnesses, no problems were noted with the pilot or the airplane prior to the accident flight. The airplane departed the airport about 1300. One witness stated that he first saw the airplane "doing its stunts" for about 4 to 5 minutes prior to the accident. He stated that the "stunts" involved "flying straight, then twisting," and also descending steeply toward the ground and "pulling it up" again. He stated that the airplane descended and pulled up about two or three times prior to the accident. Each time, the airplane would begin to "pull up" about 300 to 500 feet above the ground. During the final descent, the witness "saw him go down real steep, then was trying to bring it back. But he couldn't..." because "he just came down too far" and he "just got too close" to the ground. The witness also stated that the airplane descended "in a circular motion," and he could not remember if he heard the engine during the final descent. Another witness who resides about 3/4-mile from the accident site stated that he was working in the front of his house at the time of the accident. He stated that he looked up and first saw the airplane "flying level" from the north. He watched it for "a couple of minutes" as the airplane continued to fly around the area. No acrobatic maneuvers were observed at this time. He then looked away and continued his work. Then, he stated that he heard the airplane's engine "revving." He looked up and saw the airplane flying "level" at about 1,000 feet above the ground. He then saw the airplane "roll." The nose of the airplane then "dropped and went straight down, faster and faster at a 90 degree angle to the ground." Another witness stated that she was driving her car on 73rd West, located near the accident site, at the time of the accident. She stated that she saw the airplane for only a few seconds just prior to the accident. She first saw the airplane "going due east." The airplane was "almost level, the nose barely nose up, about 500 feet high." She stated that she could not hear any engine noise from the airplane and her automobile windows were down. She also stated that "it looked like he was trying to pull up." The airplane then performed a "perfect corkscrew to the left...a very smooth continuous roll to the left," and then "just ran out of sky" and impacted the ground left wing first. Two other witnesses were working in front of a driveway at the time of the accident. The driveway was located about 1,400 feet from the accident site. The witnesses stated that they first heard the airplane's engine prior to seeing the airplane. They indicated that the engine was "running" normally. Then, they heard the engine "die," causing them to look up. They saw the airplane flying level "about 500 feet" above the ground at this time. The airplane then "turned to the right and went upside down. The airplane "just kind of hung there" and started to go "into a flat dead spin." The airplane then continued to turn "clockwise" and began to "right itself." They stated that the engine "started back up just as he was righting himself." As soon as the engine was started, the airplane was observed to descend and "corkscrew" toward the ground. The corkscrews were "tight" at first, and then started to "get bigger and bigger." It appeared to the two witnesses that the airplane was beginning to "pull out," but it impacted the ground instead. The witnesses indicated that the airplane hit the ground "flat," and it did not appear that the airplane was gliding to a forced landing because "the engine was running" just prior to impact. No radio communications or distress calls were reported by any air traffic control facility or other pilots during the flight. PERSONNEL INFORMATION The pilot, age 63, was a certificated private pilot with a rating for single engine land airplanes. According to FAA records, the pilot was issued an FAA Third Class Medical Certificate on May 9, 1994, with no limitations. An examination of the pilot's personal logbook indicated that he had logged about 770 hours of total flight time, including 164 hours in type. AIRCRAFT INFORMATION The aircraft was home built by the pilot from plans and raw materials. Upon completion, the aircraft received an FAA Special Airworthiness Certificate as an experimental aircraft on June 1, 1992. The aircraft had a tandem-seat, single-engine, bi-wing configuration and was powered by a fuel-injected 190-horsepower Lycoming HIO-360 engine. An examination of aircraft maintenance records revealed that the airplane had received an annual inspection on July 1, 1994. No outstanding maintenance discrepancies were noted. The aircraft and engine had accumulated about 175 hours of operating time prior to the accident. Fuel receipts and the pilot's personal refueling records were examined. Based on these records, an estimated minimum of 10 gallons of fuel remained in the main fuel tank at the time of the accident. WRECKAGE AND IMPACT INFORMATION The wreckage was examined at the accident site about 3 hours after the accident by an FAA aviation safety inspector from Salt Lake City. It was examined again by the inspector on October 12, 1994, after it had been removed and secured. The engine underwent a detailed inspection on October 26, 1994, under the supervision of the Safety Board. According to the FAA inspector, the airplane wreckage was oriented along an easterly heading. The aircraft impacted level terrain about 100 feet west of powerlines. The left wing sustained greater damage than the right. The propeller had broken away from the engine and was found about 4 feet from the engine. According to the inspector, one blade "had a curl to the rear of about 10 degrees, the other blade was straight." No evidence of pre-impact mechanical flight control malfunctions were found. No evidence of fire or explosion was found. The following instrument readings were photo-documented at the accident site: Engine tachometer (forward panel) 1200 revolutions per minute Engine manifold pressure 18 inches Hg pressure Vertical speed indicator Pegged in descent Airspeed 50 miles per hour An examination of the fuel system by the inspector revealed that the main fuel tank (located forward of the passenger) was ruptured. The auxiliary fuel tank (located on the top wing) was intact and empty. The caps to both tanks were intact. The cockpit fuel tank selector was found in the MAIN tank position. The fuel pick-up "flop" tube (mounted in the main tank) was inspected; no evidence of blockage, binding, or deterioration was found. The fuel inlet screen was removed and visually examined. No contamination was present. The engine-driven fuel pump had separated from the engine and was examined. The pump actuator arm was broken and the pump could not be tested by hand. The pump housings were separated and the diaphragm and valve assemblies were found intact. Fuel was present in the pump. All four injector nozzles were removed and visually examined; all were clear and free of contamination. The fuel injection flow divider had separated from the engine and the fuel injector servo unit. The components were sent to the Safety Board Materials Laboratory in Washington, D.C. for examination. According to the metallurgist's factual report (attached): "Magnified examination on the break with the aid of a stereo microscope disclosed features indicating the separation resulting from overstress forces. No evidence of prior cracking was found." Both magnetos had separated from the engine. One of the magnetos was destroyed and could not be tested. This magneto had an impulse coupler installed and the coupler was intact. The second magneto produced sparking from all four towers when the shaft was manually rotated. The magneto's impulse coupler was intact and functionally tested. An examination of the engine did not disclose any evidence of pre-impact mechanical malfunction. Valve and gear train continuity, and cylinder compression, were established during 360 degrees of manual crankshaft rotation. No evidence of heat distress, oil starvation, or oil contamination was found. All sparkplugs were removed and visually examined; no anomalies were noted. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed on the pilot by Dr. Maureen J. Frikke, M.D., of the Utah Office of the Medical Examiner, Salt Lake City, Utah, on October 9, 1994. According to the report of examination, the immediate cause of death was "multiple blunt force injuries due to airplane crash." The report also stated: "No antemortem disease processes likely to cause pilot demise and subsequent crash of the airplane were identified by postmortem examination." A toxicological analysis (report attached) was performed on specimens taken from the pilot by the FAA Civil Aeromedical Institute, Oklahoma City. According to the report, no evidence of carboxyhemoglobin, cyanide, ethanol, or illegal drugs was detected. ADDITIONAL INFORMATION An examination of the pilot's personal log book revealed the word "rolls" in the "Remarks" column for the previous six local flights.
THE PILOT-IN-COMMAND'S ATTEMPT TO PERFORM A LOW ALTITUDE FLIGHT MANEUVER, AND HIS FAILURE TO MAINTAIN ADEQUATE AIRSPEED DURING THE MANEUVER. THIS LED TO AN UNRECOVERABLE AERODYNAMIC STALL.
Source: NTSB Aviation Accident Database
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