CEN16LA292

The pilot's failure to maintain adequate clearance from power lines. Contributing to the accident was the pilot's failure to circle over the field to identify hazards before beginning the aerial application.

The commercial pilot was performing an aerial application flight to an area that a ground crewman described as a "wire farm" due to the number of power lines present. The pilot did not complete a circling pass over the target field to identify hazards before descending for the first aerial application pass. The pilot flew over a set of power lines, activated the airplane's spray function, and completed one pass to the north. The airplane then climbed and made a left turn before descending toward the west side of the target field for a pass to the south. The pilot completed a pass on the west side, then impacted power lines on the south side of the field. The airplane continued south and impacted a corn field, where it came to rest upright. The top of the vertical stabilizer and the rudder were found near the power lines. A postaccident examination of the airplane revealed evidence of multiple wire strikes to the canopy, wire protection system, and empennage. At least one wire was deflected over the canopy, along the wire deflector cable, and cut through the vertical stabilizer and rudder. At least one wire impacted the aluminum wire protection bar and the cockpit structure consistent with the wire not deflecting over the canopy. The examination did not reveal any preimpact anomalies that would have precluded normal operation.

GPS Device Downloads A Satloc M3 Bantam GPS and a Garmin aera 510 GPS were found in the wreckage and were sent to the NTSB Recorders Laboratory for download. The combined data from the two devices was plotted on Google Earth (figure 1 and 5). The red flight path originates from the southeast and continues directly to the target field without any evidence of an initial circling pass. The areas of green represent the flight path when the airplanes spray function was on. The white lines represent the power lines that cross the flight path west to east. Figure 5 – Google Earth overlay of accident flight path Power Line Markers A few round, orange objects, similar to high visibility power line markers, were observed on the road near the accident site by a nearby landowner. The power company reported that no markers were installed on the power lines. The power company could not find any documentation to prove there were high visibility power line markers installed prior to the accident. As a result of the accident, the power company installed several high visibility power line markers on the new power lines. The Iowa Office of the State Medical Examiner, Ankeny, Iowa, completed an autopsy on the pilot and the cause of death was multiple blunt force injuries. The FAA's Bioaeronautical Sciences Research Laboratory conducted toxicology testing, which was negative for ethanol and drugs. A review of the pilot's logbooks and flight data revealed that he had accumulated 1,746.2 total flight hours and 414.1 hours the Air Tractor AT-402. The pilot had flown 114.5 hours in the preceding 30 days, all of which were in the accident airplane. The main wreckage was located in a corn field about one mile south of SKI. The field being treated was north of the accident site. A large set of power transmission lines ran east to west along the southern border of the target field (figure 1). The power lines and supporting tower structures were 80 to 90 ft tall and the power lines sagged in between each tower. A farm house and several farm buildings were located south of the power lines. Figure 1 – Google Earth overview of the accident location and flight path The wreckage debris path was oriented north to south and featured a swath cut through the mature corn, which continued to the main wreckage. The main wreckage was about 900 ft south of the power lines and 75 ft south of the initial impact area. There was a smell consistent with jet fuel and agricultural chemical around the site and the ground was damp. There was no evidence of fire. The debris path was relatively straight and began with the entire rudder on a gravel road underneath the power lines. A portion of the vertical stabilizer was found next in the debris path on the north side of the farm house. Next was the swath of cut corn and the initial ground impact point, which included debris from the bottom of the airplane (figure 2). Figure 2 – Main wreckage and debris path The forward wall of the cockpit was part of the hopper structure and was laying adjacent to the fuselage. The instrument panel remained mostly intact and undamaged. The Hobbs meter mounted in the instrument panel showed 7,008.3 hours. The center fuselage between the firewall and the cockpit was crushed. The fuselage was bent, twisted left, and came to rest next to the left wing. The horizontal stabilizers and elevators exhibited minimal damage and remained attached to the aft fuselage. The lower portion of the vertical stabilizer remained attached to the empennage and exhibited a jagged horizontal cut at the top (figure 3). Figure 3 – Left rear view of the main wreckage The right and left wings remained connected at the center splice joint. There were no prominent impact marks on the leading edge or upper surface of the wings. The bottom of the wings exhibited impact damage. The outboard section of the right flap was bent under the inboard half of the flap. The left and right ailerons and flaps remained installed in their respective positions. Both wing fuel tanks were breached at the inboard ends. The fuel caps were in place and secure. The elevator controls were impact damaged, but continuous from the control stick to the elevators. The elevators were attached to the horizontal stabilizers at the hinge points. The rudder pedals remained attached to their pivot points with the rudder cables and adjustment brackets in place. The rudder cables were continuous to the aft fuselage where they were found separated and exhibited signs of tension overload. About 15 inches of the aft end of the rudder cables remained attached to the rudder and exhibited signs of tension overload. The horn plate remained installed on the bottom of the rudder, but was bent into a "U" shape. The control stick remained attached to the floor-mounted torque tube which remained attached to the left aileron control tube through the upper pushrod and fuselage bellcrank. The trailing edge push rod was bent and separated near the inboard end and the rod end bearing remained attached to the bellcrank. From the push rod separation, the controls were continuous to the left aileron control horn. From the cockpit torque tube, the right aileron controls were continuous through the upper pushrod and fuselage bellcrank. From the fuselage bellcrank, the controls were continuous to the right aileron, except the inboard end of the pushrod that was separated where the wing was pulled away from the fuselage. The flap actuator was found in the retracted position. The trim system sustained impact damage but remained continuous and attached at all connections. The main landing gear separated from the fuselage. The left wheel and gear spring were found near the initial impact point in the debris path. The right gear spring was found near the left wingtip of and the right wheel on the right side of the fuselage. The tailwheel assembly separated from the tail spring. The four-point pilot restraint system remained fastened and the lap belt had been cut by first responders on the left side of the buckle. The shoulder harness straps had separated from the attachment points at the lap belt. Slight fraying of the shoulder harnesses was noted near the top of the seatback with no evidence of overstress failure. The engine sustained impact damage and remained attached to the respective engine mounts. The engine exhaust housing was impact damaged. The engine had separated at the "C" flange, revealing the interstage baffle and the power turbine wheel. The power turbine had damage to all blades and the interior of the engine showed significant rotational scoring signatures. The propeller hub and spinner remained attached to the engine flange. Only one propeller blade remained attached to the propeller hub. The two other blades were not found at the scene. The FAA Inspector stated that the two missing blades had been present in the debris field on his previous visit to the scene on the day of the accident. The airplane was equipped with a single curved acrylic wind screen. There was an aluminum bar in front of the wind screen and a deflector cable connected the top of the canopy to the top of the vertical stabilizer, which were installed to add protection against wire strikes. The aluminum bar was found separated from its lower base in the debris field and was bent to the left into a rough V-shape with an inside angle about 45°. At the upper end, the tubular support structure had separated from the cockpit structure and remained attached to the bar. A 6 ft piece of the deflector cable remained attached to the top of the bar. The bar had a chamfered edge on the right side that ran the entire length of the bar. The cable that was attached to the bar exhibited abrasion and damage (figure 4). Figure 4 – Damaged wire strike protection bar The upper right corner of the cockpit structure exhibited cylindrical abrasions and