History of Flight
On April 9, 2019, at 1033 central daylight time, an Air Tractor AT-502 airplane, registration N7314D, was destroyed when it collided with power transmission lines and impacted a cotton field near Harlingen, Texas. The commercial pilot was fatally injured. The flight was conducted under 14 CFR Part 137 for agricultural purposes without a flight plan. The intended operation was to spray pesticide over a cultivated cotton field.
Multiple witnesses observed the low-flying airplane descend toward the field. One witness reported the airplane flying east before executing a sharp right turn back toward the west. The airplane then pitched down, flew over a highway from east to west at low altitude, and subsequently collided with power transmission lines. Upon ground impact, the airplane exploded.
Personnel Information
The pilot began flying agricultural operations in April 1965. He first flew an Air Tractor AT-502 in September 1987 and had logged at least 7,500 flight hours in the accident airplane. According to his logbook, his final entry was for a flight review on March 24, 2016, at which time he had accumulated about 27,400 total flight hours.
Aircraft Information
The airplane's hour meter was destroyed in the postimpact fire, precluding a determination of total service time. Maintenance records indicated no unresolved airworthiness issues. The operator reported the airplane departed with 170 gallons of Jet-A fuel and 75 gallons of Malathion pesticide.
Wreckage and Impact Information
The accident site was the cotton field intended for spraying. The airplane impacted two 1.108-inch diameter, 345-kilovolt power transmission cables strung between two 136-foot-tall structures along the eastern field border. It then struck the ground about 200 feet west of the powerlines, producing a fan-shaped debris field extending approximately 100 feet from the initial impact. Wreckage distribution indicated the airplane was traveling west-northwest at ground impact. Red navigation lens material from the left wingtip was found at the initial ground impact point.
The main wreckage, comprising the fuselage, empennage, right wing, engine, and propeller, exhibited extensive fire damage from a prolonged postimpact ground fire. All structural components and flight control surfaces were identified at the site. Flight control continuity could not be established due to damage, but observed separations were consistent with overstress or fire damage. The left wing was highly fragmented. Two transmission cables were found conjoined with the main wreckage: one wrapped around the engine and propeller shaft, and the other around the wing carry-through structure, right wing, and fuselage. The forward face of the left main wing spar had broad vertical marks 3 to 6 feet from the airplane centerline, consistent with contact with a large-diameter power transmission cable. The right wing was largely intact with fire damage to its inboard portion.
Engine control continuity could not be established due to impact and fire damage. The first-stage compressor blades exhibited tip rub and had ingested dirt and organic matter. The turbine section showed rotational scoring on the compressor turbine disc and blades from contact with the power turbine vane and baffle. Most power turbine blades had separated from the disc; several blade roots and tips were found in the debris field ahead of the main wreckage. The remaining turbine blades were displaced forward and fractured near midspan. The propeller remained attached to the engine; its three blades exhibited spanwise twisting. Two blades segmented during impact, and one intact blade had leading and trailing edge gouging near the tip, with minor chordwise scratches at midspan.
Postaccident examination revealed no anomalies that would have prevented normal operation prior to the collision with the high-voltage power lines.
Medical and Pathological Information
An autopsy conducted by the Cameron County Forensic Department identified blunt force trauma as the cause of death. No significant natural disease was found. Toxicological analysis by the FAA's Forensic Sciences Laboratory detected 0.605 µg/mL of diphenhydramine in blood and diphenhydramine in liver samples. No carboxyhemoglobin or ethanol was detected. Diphenhydramine is a sedating antihistamine commonly used in over-the-counter cold, allergy, and insomnia medications. The therapeutic range is 0.025 to 0.100 µg/mL with a half-life of 3 to 14 hours. Postmortem redistribution may elevate central levels.