N4956XRockwell International S-2R

On August 10, 2021, at 0740 central daylight time, a Rockwell International S2R agricultural airplane, N4956X, was substantially damaged when it was involved in an accident near Strasburg, North Dakota. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 137 aerial application flight.

An employee of the pilot, who loaded the chemical on the airplane, stated that she met the pilot at the loading pad at 0630. She loaded the hopper with chemical, and the pilot departed about 0645. The pilot returned to the airport at 0721 after he sprayed the first field. The airplane was rinsed and loaded with a new chemical; the pilot departed again to spray a sunflower field.

A colleague of the pilot, who was familiar with the operation, stated that the pilot was completing his second aerial application flight of the day and intended to apply insecticide to a sunflower field. He and the pilot had sprayed this field many times before, which was always done in a north-south racetrack pattern. He had never seen the pilot spray this field in an east-west pattern before and stated that it should not be done due to the large powerlines on the west side.

A witness driving eastbound observed the airplane flying west after it exited the sunflower field. As the airplane flew under the three power lines, the tail clipped the second line, and the airplane collided with the last line, then crashed onto a road, and slid into a field. Figure 1 shows the airplane’s flight track plotted on Google Earth. The field being sprayed is highlighted in red, and the power lines on the west side of the field are shown in yellow.

Figure 1. Google Earth overlay of the accident area. Google Earth overlays are not representative of weather or lighting conditions during the accident flight.

The airplane’s maintenance logbooks were not located during the investigation.

The airplane’s maintenance logbooks were not located during the investigation.

A postaccident examination of the power lines revealed damage to all three lines on the west side of the target field. Of the damaged lines, the east side line was the least damaged and partially intact. The center line was mostly severed with less than a third of the wire strands intact. The west side line was completely severed and lying on the ground.

Airplane debris was found underneath the damaged lines and on the ground leading toward the main wreckage. The wreckage distribution was consistent with the airplane impacting the ground, sliding over a road, and coming to rest inverted in an adjacent field. There was a propeller slash mark found in the debris field near the main wreckage. The engine and propeller separated from the airplane and were found to the east of the main wreckage in the debris field.

Examination of the airplane revealed evidence that the right wing collided with a power line in a right-wing-high, left-wing-low attitude. The outboard leading edge of the right wing contained wire strike marks. Part of the right wing leading edge metal panel wrapped around the wire, separated from the wing, and was found on the ground underneath the lines. The top pieces of the rudder and horizontal stabilizer were found underneath the lines and exhibited black sooting and burn marks, consistent with electrical arcing damage. The adjoining piece of rudder was separated from the rest of the rudder and empennage. A small piece of the fiberglass horizontal stabilizer had been cut and was found under the lines. The remainder of the airplane came to rest inverted in the field west of the power lines. The airplane’s flight controls were continuous from the cockpit to the respective control surfaces. The propeller blades exhibited rearward bends and chordwise scratches. The airplane examination revealed no evidence of preimpact mechanical malfunctions or failure that would have precluded normal operation.

The airplane’s Satloc G4 GPS and Electronics International MVP-50T engine monitor were removed and sent to the NTSB Vehicle Recorders Laboratory for data extraction.

The SATLOC G4 GPS showed signs of impact damage; it was disassembled, and the internal storage was removed. Data extracted included 32 log files recorded from July 11, 2021, through August 10, 2021. For the accident flight, the recording did not begin until the aircraft reached the accident location.

The pilot’s colleague reported that the pilot had recently experienced operational issues with the GPS and that the issues with the GPS were more operational in that the pilot was not “tech savvy.” The pilot’s employee stated that she had never witnessed nor heard the pilot mention issues with the GPS. There were no anomalies noted during the device examination and data extraction.

The MVP-50T exhibited minor impact damage; the device powered on normally and data was extracted. The data extracted included 433 sessions between April 6, 2017, and August 10, 2021. The accident flight was the 433rd session, recorded starting at 3:41:44 local time and ending at 4:43:31 local time on August 10, 2021. Only a single engine parameter was recorded. The times recorded on the last log file did not correspond to the time of the accident. The last log file was the only flight with a date of August 10, 2021. GPS information was not present in the MVP-50T log file. The duration of the file was similar to the SATLOC data file, which did contain GPS timing information. Because a direct time correlation between the MVP-50T data and the SATLOC data was not possible, the MVP-50T data was not used for the flight track images. The data do not show any anomalies.