EUDORA, AR, USA
N6093U
Air Tractor 502B
Witnesses observed the aircraft maneuvering at about 1,500 to 2,500 feet. One witness reported the aircraft appeared as though it was going to do a 'loop;' however, it 'stalled.' At one point it looked as though the aircraft would just roll out and continue flying, but the 'right wing appeared to stall' and the aircraft entered into 'an inverted flat spin.' At about 200 to 300 feet agl, the aircraft nosed over to a more vertical position at which time the aircraft went behind some trees. A witness reported that the 'engine never stopped running.' No anomalies were found with the airframe or engine that would have prevented normal operation.
HISTORY OF FLIGHT On January 16, 1998, about 1450 central standard time, an Air Tractor 502B agricultural airplane, N6093U, owned and operated by Snow Flying Service, Inc., of McGehee, Arkansas, was destroyed following a loss of control while maneuvering near Eudora, Arkansas. Visual meteorological conditions prevailed, and a flight plan was not filed for the Title 14 CFR Part 91 personal flight. The commercial pilot, sole occupant of the airplane, was fatally injured. The flight originated from the Hensley Flying Service Airstrip, Eudora, Arkansas, about 1425. Snow Flying Service's pilot Troy Meaux, reported to the NTSB investigator-in-charge (IIC) that the accident aircraft, N60934, "has always been a mechanically solid aircraft with little or no trouble." The aircraft "seemed to carry a load very well," but he had a concern about how it turned. At times it seemed that in a "tight turn," usually to the right, it would give him a feeling as though the aircraft wanted to "tuck the wing under." Throughout the past year he has had "several people look at the aircraft to see if maybe they might know what would cause it to not turn very well." Nothing was ever found wrong with the aircraft. Troy further reported that he had talked several times with the pilot of the accident airplane, Roger D. Hensley, Jr., about his aircraft. Roger informed him that he also had an AT-502B, and invited him to fly his aircraft to see if it flew any different. On the day of the accident, Troy flew the accident aircraft, to the Hensley Flying Service Airstrip. He wanted to put the "two aircraft side by side and compare them as far as the wing angles and flap angles and things of that nature if by chance we might find something different between the two." After Troy arrived at the Hensley Flying Service Airstrip, Roger informed him that after he flew his airplane, N60762, he could fly it. Troy stated that he observed Roger do steep climbs and turns, stalls, and a "loop." After he landed, Roger told Troy to take his aircraft and "see if it felt the same way as his." At this time Roger requested to fly Troy's aircraft, and Troy agreed. "About 2:25, before I landed, Roger took off in my aircraft, I watched him climb to altitude and do a few stalls." Troy then landed his aircraft, shut it down, and "climbed out to watch him flying my aircraft." Troy reported that as he was observing the aircraft, it seemed as though it was going to perform a "loop," but as the aircraft approached the inverted position, the tail dropped. The aircraft continued in inverted flight for about 2.5 seconds. Then the aircraft's tail continued to drop, and it appeared as though the aircraft was "trying to go vertical." As the aircraft "became vertical it quit climbing and hung there for just a second." It then "stalled" to the right, "the nose of the aircraft fell over and was headed for the ground." At that point it looked as though the aircraft would just roll out and continue flying; however the right wing appeared to "stall" and the aircraft entered into "an inverted flat spin." The aircraft was approximately 1,500 feet as it entered the inverted flat spin. He also reported that at about 200 to 300 feet agl, the aircraft nosed over to a more vertical position at which time the aircraft went behind some trees. A witness, who was also located at the Hensley Flying Service Airstrip, reported to the IIC that he observed the aircraft climb to 2,000 or 2,500 feet. The aircraft made one turn to the right, and then as it began to make another right turn, its nose dropped and started to spin. "I thought he was going to bring the plane back up but he kept going down." The witness further reported that the "engine never stopped running." Another eye witness, who was on a tractor, reported to the IIC that he observed the aircraft inverted with its nose down spinning clockwise. He observed the aircraft for about 6 to 10 seconds, and didn't see it complete a revolution. The witness further reported that he could not hear the aircraft's engine because of the tractor. PERSONNEL INFORMATION The 25 year old pilot became qualified as a private pilot on May 18, 1993, and on February 17, 1994, he obtained a commercial pilot certificate. According to entries in the pilot's flight logbooks, he began flying an Air Tractor AT-502B aerial application airplane in July 1996, and had accumulated 1,966 hours in this make and model aircraft. The Air Tractor AT-502B airplane, N60762, which the pilot was accustomed to flying, had a Pratt & Whitney PT6A-34AG turbine engine rated at 750 horsepower. A review of the pilot's flight logbooks did not reveal any aerobatics training. AIRCRAFT INFORMATION The 1996 Air Tractor AT-502B was a single place, single engine aerial application airplane, which could hold a maximum hopper load of 4,100 pounds. The aircraft had a Pratt & Whitney PT6A-15AG turbine engine rated at 680 horsepower. According to the flight manual, "this aircraft must be operated in the restricted category in accordance with placards and markings in the cockpit. No aerobatic maneuvers, including spins." A review of the airframe and engine records available to the IIC, did not reveal evidence of any anomalies or uncorrected maintenance defects. The aircraft's maximum takeoff weight is 8,000 pounds and an estimate of the weight of the aircraft at the time of the accident placed it within weight and balance limits. WRECKAGE IMPACT INFORMATION The aircraft was located approximately 2 miles south of the Hensley Flying Service Airstrip and about 1.5 miles southwest of Eudora in a catfish pond. Examination of the accident site revealed that the aircraft came to rest inverted about 100 feet east of the pond's west bank in about 2 to 3 feet of water. The airplane's final resting heading was measured at 270 degrees magnetic. See the enclosed wreckage diagram for wreckage distribution details. The fuselage was displaced to the left just aft of the cockpit. The cockpit was deformed downward and aft. The leading edges of both wings were compressed downward and aft. The front and rear spars were compressed toward each other. The vertical fin and rudder were partially separated from the empennage and folder over to the right. See the enclosed Air Tractor report for details. Flight control cable/rod continuity was established from the cockpit to the aileron, flap and rudder surfaces. Control continuity could not be established to the elevator due to the push rod being separated from the elevator control horns. The elevator push rod end bolt and the pivot point bolt were not found; however, the left elevator horn had an imprint of what appeared to be a washer at the push rod hole. The right elevator control horn was found fractured but still attached to the torque tube. The separated part of the elevator control horn was not found. The fractured elevator pitch horn was sent to the NTSB Materials Laboratory in Washington D.C., for examination. The engine was found pushed aft into the firewall, and its mounts were fractured in several places. The engine's "C" flange was opened about one inch at the top, and majority of the "C" flange bolts were found sheared. The exhaust case was buckled and compressed. Impact damage precluded rotating the compressor and power sections. The propeller assembly remained attached to the propeller flange. Two of the three blades were bent about 80 degrees aft. One of these blades had a large gouge in the leading edge at its tip. The third blade exhibited forward "S" bending and twisting. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was not performed at the discretion of the NTSB investigator-in-charge. Toxicological findings were negative. TESTS AND RESEARCH The elevator pitch horn was examined at the NTSB Materials Laboratory and according to the NTSB metallurgist, the fracture's characteristics were consistent with an overstress separation. See the enclosed Metallurgist's Factual Report. ADDITIONAL DATA The aircraft wreckage was released to the owner.
The pilot's failure to maintain adequate airspeed while attempting an aerobatic manuever
Source: NTSB Aviation Accident Database
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