According to the pilot’s spouse, the pilot was flying that day to practice aerobatic routines in preparation for seeking a qualification to fly in air show performances.
According to FAA ADS-B flight track data, the Aviat S-1-11B departed to the southeast from Whifferdill Airport (TN77) in Chapmansboro, Tennessee, about 1345. The flight track showed that, after overflying the airport twice, the airplane spent the remainder of the flight about one mile south of the airport in the waivered aerobatic practice box performing low-altitude maneuvers between 400 and 2,000 feet AGL. The final ADS-B flight track data point was recorded 12 minutes after takeoff, at 1357.
According to a witness who was on a kayak on the Cumberland River about a half mile south of the accident site, the airplane had been performing a variety of aerobatic maneuvers at low altitude. He told investigators that the airplane’s engine sound would go quiet and then “rev” back up during the maneuvering. He recorded several videos of the airplane as it flew, including a video that was about two minutes long that captured the final moments of the flight.
In the last few seconds of the video, the airplane entered a climb and completed a 4-point aileron roll. It continued to climb briefly after the roll before continuing out of the camera’s view.
Review of ADS-B data showed that the airplane’s altitude for this final maneuver was between 700 and 1,800 feet AGL.
The airplane reappeared on video in an orientation consistent with an inverted flat spin, rotating slightly nose left, and in a rapid vertical descent toward the river. An increase in engine rpm could be heard during the final few seconds of the video, and engine noise could be heard throughout the flat spin, even after the airplane disappeared from view below the tree line.
The airplane was substantially damaged in the accident. The commercial pilot was fatally injured.
According to the witness on the river, there was a slight breeze with no significant weather at the time of the accident. Routine surface observations from the surrounding area confirmed that no significant weather, including clouds or precipitation, was present at the time of the accident. A hurricane was tracking toward the area from the south and was expected to produce rain in the area for the remainder of the week. The pilot’s spouse recalled that the pilot was “trying to get his first practice flight in before the rain came the next day.”
According to FAA registration records, the pilot bought the airplane on June 3, 2022. An annual inspection was performed shortly before the purchase on April 19, 2022, at tachometer time of 2,398.78 hours. Two annual inspections were performed since the pilot had purchased the airplane: One on July 7, 2023, at 2,408.03 hours, and the most recent inspection on Aug. 15, 2024, at 2,447.29 hours (about a month before the Sept. 23, 2024, accident). The airplane had accumulated at least 39.3 hours since it was purchased and, according to the pilot’s spouse, he was the only person who had flown the plane since the purchase.
The pilot based the airplane out of TN77, which was a private-use, fly-in community and airport. ADS-B data showed the airplane departed from Runway 15, which was a 2,000-foot turf runway. The Whifferdill practice aerobatics box was active, with an associated NOTAM in effect at the time of the accident. The box was located immediately south of the airport over the Cumberland River, with each of its four boundaries 1 mile in length extending from 500 feet AGL to 3,500 feet mean sea level (MSL).
The airplane crashed in shallow water in the Cumberland River about 150 feet from the last observed ADS-B position. The airplane was inverted and partially submerged in the river. A small fuel slick was evident in the water around the wreckage. The wreckage was recovered from the river and transported to a salvage facility for examination.
The airplane remained intact except for the canopy, which was not recovered.
Flight control continuity was confirmed from the cockpit to all flight control surfaces. The top of the rudder and vertical stabilizer were bent 90° to the right. The top of the airframe exhibited downward crushing, while the bottom of the fuselage structure was relatively free of damage. The landing gear remained intact and sustained little damage. The fuel header tank was breached on impact.
The engine remained intact and was free of major impact damage, but contained a substantial amount of mud and debris, consistent with being submerged in water.
Crankshaft and camshaft continuity and thumb compression, were observed on all cylinders. The top and bottom spark plugs exhibited normal combustion signatures and the oil filter displayed no evidence of metal contamination.
The left magneto produced spark when its input driveshaft was rotated by hand, but the right magneto was too waterlogged to produce a spark. All three propeller blades had splintered and separated near the propeller hub on impact.
Probable Cause: The pilot’s loss of airplane control while performing an aerobatic maneuver, which resulted in the airplane entering an inverted flat spin at an altitude too low for recovery.
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This September 2024 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
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