History of Flight
On March 19, 2017, at approximately 1600 central daylight time, an Air Tractor AT-602, registration N2049D, collided with trees and terrain near Minter City, Mississippi. The aircraft was owned and operated by Sturdivant Brothers Flying Service, Inc., conducting a Title 14 Code of Federal Regulations Part 137 aerial application flight. The commercial pilot, the sole occupant, was fatally injured, and the airplane was destroyed by impact and postcrash fire. Visual meteorological conditions prevailed, and no flight plan was filed for the local flight, which had originated about 30 minutes earlier from the company airstrip in Glendora, Mississippi.
The pilot departed the airstrip with each wing fuel tank filled to approximately three-quarters capacity and the hopper containing 375 gallons of mixed water and chemicals. After takeoff, the pilot proceeded toward the intended spray field. Although no eyewitnesses observed the accident, an individual living adjacent to the intended application field reported hearing an airplane fly over his house. He noted that the airplane sounded normal, but about 10 to 15 seconds later, he heard a "pop" sound followed by an explosion. He went outside, saw a fire, and a friend called 911. He drove to the site and observed damage to trees and airplane parts located away from the main wreckage. The fire department arrived approximately 20 minutes later and extinguished the fire, which was mostly confined to the cockpit area. Inspection of the intended spray field revealed evidence of "burning" of weeds consistent with some application of the hopper contents, but the extent of the application could not be determined.
Personnel Information
The pilot, age 68, held a commercial pilot certificate with a rating for airplane single-engine land. He held a Federal Aviation Administration second-class medical certificate issued January 16, 2017, with a limitation for near vision. He reported 29,943 total hours of flight experience on his last medical application. His last flight review occurred on January 30, 2017. The pilot was hired by the operator in March 2011 and, at that time, had accrued about 24,613 hours. His title was Chief Supervisor/Pilot. The pilot's sister reported that she spoke with him the day before the accident, during which he mentioned having a cold.
Aircraft Information
The accident airplane was manufactured in 2012 by Air Tractor, Inc., serial number 602-1219. It was powered by a Pratt & Whitney Canada PT6A-60AG engine rated at 1,050 shaft horsepower for takeoff, equipped with a Hartzell HC-B5MP-3C/M10876ANS propeller. The last annual inspection was performed on November 8, 2016, at an airplane total time of 2,752 hours. The aircraft was equipped with an AgJunction Satloc G4 GPS receiver, but due to heat damage to its two internal memory cards, no data could be extracted.
Meteorological Information
At 1553, a surface observation at Greenville Mid-Delta Airport (GLH), Greenville, Mississippi, about 18 nautical miles south-southwest of the accident site, reported calm wind, 10 miles visibility, clear skies, temperature 26°C, dew point 8°C, and an altimeter setting of 30.21 inches of mercury.
Wreckage and Impact Information
The accident site was located among trees at the southern portion of an open field, about 760 feet east of the eastern edge of the 75-acre field intended for spraying. Damage to trees was observed between 15 and 20 feet above ground level on a magnetic heading of about 280°. Airplane debris was scattered among the trees and in the open field north of the energy path between the first tree contact and the main wreckage, which was about 282 feet and 280° from the first tree contact. Damage to trees at decreasing heights was noted along the energy path. The main wreckage had an odor of Jet A fuel.
Components found farthest east from the fuselage included portions of the left wingtip, outboard end of the left main spar, leading edge of the left wing with semi-circular damage, and other parts. The semi-circular impression on the left wing leading edge correlated with impact damage on a standing tree. The wing damage and lack of ground damage under the right wingtip were consistent with a wings-level attitude at tree impact.
Examination revealed extensive heat damage to the fuselage, cockpit, and sections of both wings. Both wings remained secured at the center splice, with all main spar attach bolts sheared at the fuselage attach point. The left wing main spar was "S" shaped and fractured about 5 feet 10 inches outboard of the outboard wing splice. The left aileron trim tab was pulled from the aileron, but the pushrod remained connected; the trim position could not be determined. The cockpit sustained extensive fire damage, but the occupiable space was not compromised. The pilot's seat remained attached with shoulder harness airbags, which exhibited heat damage. The emergency dump handle was in the locked (non-dumping) position. The power, condition, and propeller controls were full aft, consistent with being pulled during engine separation. The flap actuator indicated about 5° of flap deflection.
All flight control surfaces and counterweights were accounted for. Flight control continuity was confirmed for roll, pitch, yaw, and right aileron droop system, though heat damage and overload failures were noted. Examination of the left aileron droop system revealed separated pushrods. The gatebox shutoff valve was in the open position; the spray valve was destroyed. The engine remained attached at all four mount points but separated from the airframe. The engine showed no evidence of preimpact failure or malfunction. The fuel control unit and propeller governor were retained and examined; damage precluded operational testing, but no preimpact failure or malfunction was found.
Tree limbs with smooth angular cuts and gray color transfer consistent with propeller contact were retained. One propeller blade was rotated toward low pitch, with a counterweight angle of about 23° corresponding to a blade angle of about 11°. The propeller was not feathered at impact, and no preimpact failure or malfunction was evident.
Medical and Pathological Information
The Mississippi State Medical Examiner performed a postmortem examination. No soot aspiration was noted. The cause of death was reported as "asphyxia of undetermined etiology." Forensic toxicological testing by the FAA Bioaeronautical Sciences Research Laboratory detected dextromethorphan, dextrorphan, pseudoephedrine, doxylamine (0.145 ug/ml in cardiac blood), and acetaminophen in urine. Dextromethorphan, pseudoephedrine, and acetaminophen are not considered impairing in usual doses. Doxylamine is a first-generation sedating antihistamine that may cause central nervous system depression and impair mental alertness; usual blood levels associated with effects are between 0.050 and 0.150 ug/ml.
Tests and Research
According to a representative of the airplane manufacturer, agricultural turn distances from the spray field for turbine-powered airplanes vary significantly depending on aircraft type, spraying speed, pilot technique, wind speed and direction, weight, and local obstacles. Typically, pilots make turns within 1/4 to 1/2 mile from the field edge.