CEN22FA288

During an aerial application flight, the helicopter impacted power lines that were near the top of the canopy of a mesquite tree grove. The helicopter was destroyed during the impact. No radio or distress calls were heard from the pilot before the collision. Detailed examinations of the flight controls, airframe, and engine did not reveal any preimpact mechanical malfunctions or failures that would have precluded normal operation. Examination of the engine revealed multiple transfer marks and scoring consistent with engine rotation at the time of impact. The pilot's toxicology results indicated that he had used a cannabis product. The precise timing of his cannabis use, and whether he was experiencing impairing effects from that use at the time of the accident, could not be determined from available evidence. Thus, it is unknown whether effects of the pilot's cannabis use contributed to the accident. The pilot's autopsy identified mild coronary artery disease and mild left ventricular hypertrophy of the heart. This heart disease conveyed some increased risk of a sudden impairing or incapacitating cardiac event, such as heart attack or abnormal heartbeat. Based on available medical evidence, it was unlikely that the pilot's mild heart disease contributed to the accident.

Review of maintenance logbooks for the airframe and engine did not reveal any uncorrected defects and the annual inspections were up to date. On June 26, 2022, about 0830 central daylight time, a Robinson R44 helicopter, N4124D, was destroyed when it was involved in an accident near Blackwell, Texas. The pilot sustained fatal injuries. The helicopter was operated as a Title 14 Code of Federal Regulations Part 137 aerial application flight. The purpose of the aerial application flight was to apply selective herbicide targeting a large grove of mesquite trees. After loading the herbicides near the target spray area, the pilot took off and completed 2 or 3 passes over the mesquite grove. After about 3 to 4 minutes, the person who loaded the helicopter with chemicals heard a metallic-type impact sound coming from the direction of where the helicopter was spraying. He subsequently heard an impact sound and an abrupt end to the engine and rotor blade noise coming from that direction. He responded to the accident site as quickly as possible. There were no direct witnesses to the accident. There were no radio or distress calls heard from the pilot before the accident. An autopsy on the pilot was conducted at South Plains Forensic Pathology, Lubbock, Texas. The cause of death was blunt force injuries. The pilot's autopsy identified mild coronary artery disease and mild left ventricular hypertrophy of the heart. Toxicological tests were performed at the Federal Aviation Administration Forensic Sciences Laboratory, Oklahoma City, Oklahoma. 3.5 ng/mL Tetrahydrocannabinol (THC) was identified in heart blood, 11-hydroxy-delta-9-THC was detected in urine but not in the heart blood. Carboxy-delta-9-THC was detected in urine and 9.4 ng/mL in heart blood. A series of power poles running southwest to northeast carried two wires through the mesquite grove canopy. The poles measured about 23 ft tall with one wire on top and the second wire about 3 ft below the top wire. Both wires were found separated from the pole nearest the main wreckage and the top wire was broken in that area. The next pole to the northeast was shattered at the base and came to rest 100 ft to the south with the top wire separated and the lower wire still secure. On the next pole to the southwest, the top wire was separated, and the lower wire remained secure. The lower wire was found entangled around the main wreckage and had black paint transfer marks consistent with the helicopter’s paint. The top wire on both sides of the break had black paint transfer marks. The debris field extended 315 ft, oriented north and south, beginning 130 ft south of the closest pole and consisted mostly of tailcone and tail rotor drive components. The helicopter impacted the ground in a nose-low and left-side-low attitude. There was no postimpact fire. There was no indication of electrical arcing visible on the wires or wreckage. The main wreckage came to rest on a southerly heading about 320 ft south of theclosest pole with the top wire entangled in the helicopter fuselage. The first point of ground contact was 3 to 4 ft north of the main wreckage. Wires were found wrapped around the leading edge of the main rotor swashplate and score marks consistent with rotation were visible. More wires were found wrapped around the main rotor mast fairing, over the right side of the cabin roof, and down along the aft part of the cabin door. There were more wire score marks found on the hydraulic servo below the main rotor swashplate. Detailed examination of the helicopter airframe, flight controls, and engine did not reveal any preimpact anomalies. All separations in the flight controls were consistent with impact damage. The frame tube adjacent to the forward face of the upper sheave near the engine exhibited scuff marks in the direction of engine rotation. The forward face of the sheave exhibited score marks around its outer edge. There were black transfer marks on the tube frame consistent with impact from the adjacent engine drive belts.