CEN23FA409

The pilot was conducting an aerial application flight when the airplane’s left wing impacted a guy wire attached to a power line structure. The impact with the guy wire occurred while the airplane was flying along the edge of the field being sprayed. The outboard 7 ft of the left wing and the left aileron separated during the impact with the guy wire. The airplane subsequently crashed in a cornfield about 0.3 mile from the guy wire impact. Examination of the airplane wreckage revealed no evidence of a preimpact malfunction that would have prevented its normal operation. A review of recorded engine monitor data revealed no evidence of an engine malfunction or failure during the flight. Day visual meteorological conditions existed, and the position of the sun at high noon would not have negatively affected the pilot’s view ahead of the airplane. The pilot’s autopsy and postmortem toxicology tests did not reveal any evidence of medical incapacitation or impairment.

According to the airplane maintainer, on August 3, 2023, a 100-hour inspection of the engine was completed at 98.6 hours total time since new. On August 28, 2023, a 300-hour inspection of the airframe and 100-hour inspection of the engine was completed at 296.8 hours total time since new. According to data recovered from the airplane’s digital engine monitoring system, at the time of the accident, the airplane hour meter indicated 415.88 hours and the engine hour meter indicated 324.17 hours. The engine monitor had recorded 124 engine start cycles and 526 takeoffs. On September 12, 2023, about 1200 central daylight time, a Thrush Aircraft LLC S2R-T660 airplane, N710TY, was substantially damaged during an accident near Ardoch, North Dakota. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 137 aerial-application flight. The purpose of the flight was to spray a sunflower field. The airplane was operated from a private airstrip near Osla, Minnesota. According to data recovered from the airplane’s engine monitor, at 1152 the engine was set to takeoff power. Based on flight track data recovered from the airplane’s spray system, about 7 minutes after takeoff, the airplane approached the intended field from the south and then flew around the perimeter of the field to be sprayed, as shown in figure 1. The flight track data showed that the airplane initially flew north along the east edge of the field before it completed a left 180° turn to reverse course and continue south along the west edge of the field. The airplane then flew south while remaining west of power lines that ran north/south along the west edge of the field. As the airplane flew south the left wing impacted a guy wire that was attached to a power line structure. Figure 1. Plot of airplane’s ground track around the field. The outboard 7 ft of the left wing and the left aileron separated from the left wing during the impact with the guy wire and were subsequently found in an adjacent soybean field. The separated portion of the left wing exhibited evidence of a wire strike through the wing leading edge and along the forward spar, as shown in figures 2 and 3. The airplane continued south about 0.3 mile before it crashed in a cornfield on an east-southeast trajectory, as shown in figure 4. At 1200:28, the final recorded flight track point was about 172 ft west-northwest of the initial ground impact in the cornfield. Figure 2. Separated outboard portion of the left wing and aileron. Figure 3. Separated portion of left wing with guy wire damage. Figure 4. Plot of the airplane’s ground track at the end of the flight with the location of assorted airplane components and the main wreckage identified. The University of North Dakota Forensic Pathology Department performed the pilot’s autopsy at the request of the Grand Forks County Coroner’s Office. According to the pilot’s autopsy report, his cause of death was multiple traumatic injuries, andthe manner of death was accident. FAA Forensic Sciences Laboratory toxicological testing of postmortem specimens from the pilot did not detect any carboxyhemoglobin, ethanol, glucose, or tested-for drugs. A review of recorded engine monitor data revealed that, in the moments before ground impact, the gas generator was operating at 96.4%, the propeller was rotating at 1,520 rpm, the engine torque was 39.5 psi, the inter-turbine temperature was 702° C, the fuel flow was 88.2 gallons per hour, the fuel pressure was 21 psi, and the oil pressure was 119 psi. The airplane impacted a cornfield in a left-wing-down and nose-down attitude. The main wreckage was located about 155 ft on 101° bearing from the initial ground impact. The impact crater was located about 50 ft east-southeast of the initial impact point. An impact crater, containing one propeller blade, was located about 50 ft east-southeast of the initial impact point. The engine, propeller, and main landing gear were separated. The airplane came to rest upright in a nose-down attitude on a northeast heading, as shown in figure 5. The fuselage and cockpit were resting on the separated wing, which was found inverted. Except for the previously discussed outboard 7 ft of the left wing and left aileron, all structural components and flight control surfaces were located at the accident site. Examination of the airplane wreckage revealed no evidence of a preimpact malfunction that would have prevented its normal operation. Figure 5. Main wreckage at the accident site. The elevators, ailerons, rudder, trim tabs, and flaps were accounted for during the onsite examination. Flight control continuity from the cockpit to each flight control surface could not be confirmed due to impact damage. However, all control cable and push/pull control tube separations were consistent with impact-related damage or cuts made to facilitate wreckage recovery. The flaps appeared to be fully retracted. The right wing fuel tank contained fuel, which was observed to drain through a breach in the fuel tank during wreckage recovery. The engine showed evidence of high-velocity impact with terrain and subsequent separation from the main airframe. The engine came to rest about 60 ft beyond the main wreckage. Examination of the engine did not reveal any evidence of a preimpact mechanical malfunction or failure. The propeller assembly separated from the propeller shaft flange during impact. Two blades impact-separated from the propeller hub and were found in the debris field. Two of the three blades that remained attached to the assembly exhibited forward-bending in the thrust direction, twisted towards high pitch, and slipped in the retention clamps towards high pitch. Three of the five blades exhibited aft-bending and twisting towards low pitch in varying degrees. All blades exhibited varying degrees of chordwise rotational scoring, leading edge gouging, and bending opposite direction of rotation. The power line structure, asshown in figure 6, shows two of three guy wires attached. The third, middle guy wire, separated from the structure during the impact but remained attached to the ground anchor. The 3/8-inch outside diameter guy wire normally attached to the pole crossarm near the top of the 73 ft tall pole. According to the power company, the guy wire was about 95 ft long and attached to the pole crossarm about 65 ft above ground level. The guy wire was anchored to the ground about 62 ft west of the pole. Examination of the guy wire revealed damage about 82 ft from the ground anchor. Figure 6. Power line structure with damaged guy wire.