History of Flight
On July 1, 2014, at approximately 1730 central daylight time, an Air Tractor AT-602 (registration N91331) operated by Shannon Agricultural Flying, Inc., was destroyed when it struck a bean field in Clarksdale, Mississippi. The commercial pilot, who was the sole occupant, sustained fatal injuries. Visual meteorological conditions prevailed, and the flight, which had departed from Shannon Field (02CD), was conducted under Part 137 without a flight plan.
According to company personnel and onboard GPS data, the airplane was applying fertilizer in an east-west racetrack pattern. After each leg, the pilot made a 20- to 30-degree left turn followed by a right turn to reverse course. The GPS track indicated the airplane was on its fourth circuit when data ended before the final turn.
A witness, mowing his lawn, observed the airplane pass overhead at about 150 feet above ground. He heard the engine running above the mower noise and saw the airplane turn right to the north, with its wings becoming vertical. The airplane then impacted the ground, ejecting smoke and fertilizer. The witness found the pilot unresponsive.
Personnel Information
The pilot, aged 58, held a commercial pilot certificate with an airplane single-engine land rating. His most recent FAA second-class medical certificate was issued February 27, 2014. His logbook recorded 12,051 total flight hours, with 4,358 hours in the accident make and model. Hobbs times from a calendar in the wreckage showed 8.2 hours of operation the previous day and 6.3 hours on the accident day before the flight, plus an additional 0.3 hours on the Hobbs meter after the flight.
Aircraft Information
The low-wing, conventional landing gear agricultural aircraft was powered by a Pratt & Whitney Canada PT6A-60AG engine driving a Hartzell five-bladed constant-speed propeller with feathering and reversing. Propeller rotation was clockwise as viewed from the rear. The latest annual inspection was recorded on November 25, 2013, at 5,200 operating hours.
Meteorological Information
Weather reported at an airport about 10 nautical miles north at 1735 included clear skies, wind from 200 degrees true at 9 knots, temperature 32°C, dew point 24°C, and altimeter 29.90 inches Hg.
Wreckage and Impact
Initial impact occurred on flat terrain near coordinates 34°06.34'N, 090°34.26'W, elevation about 160 feet. The wreckage path, oriented approximately 360 degrees magnetic, began with green lens material and included airplane parts along an almost straight line. About 75 feet from the initial point, a 3-foot-deep, 10-foot-long crater held the propeller hub and four blades partially embedded. The fifth blade and the rest of the airplane lay beyond. The aircraft was fragmented, but all flight control surfaces were present. Cockpit and rollover structure were intact. Flight control continuity was confirmed from cockpit to rudder and elevator, though push rods and bellcranks to ailerons were fractured.
At a storage facility, the engine was partially disassembled. Soil was found in the gas generator case and combustion section. Compressor turbine blade tips showed smearing, and the turbine shroud had circumferential rubbing. The compressor disc outer rim exhibited rubbing with heat discoloration, consistent with the engine under power at impact. All five propeller blades showed evidence; blades 1-3 remained attached, while 4 and 5 fractured off. Witness marks indicated the propeller pitch was in the normal operating range, not feathered, at impact.
Medical and Pathological Information
An autopsy at the Mississippi State Medical Examiner's Office determined the cause of death as multiple blunt force injuries. Toxicological testing by the FAA Forensic Toxicology Research Team found no anomalies.
Additional Information
The FAA's Pilot's Handbook of Aeronautical Knowledge notes that stall speed increases in level turns due to added load, requiring increased angle of attack, and that excessive angle of attack leads to stall. The Airplane Flying Handbook states that accelerated maneuver stalls occur at higher indicated airspeeds when maneuvering loads are imposed, and such stalls can be more rapid and unexpected.