N4191XRockwell International S-2R · 1974

On June 6, 2016, about 0745 Pacific daylight time, a Rockwell International S-2R restricted-category agricultural airplane, N4191X was substantially damaged during a collision with guy wires, powerlines, and trees while engaged in an aerial application flight about 3 nautical miles (nm) west of De Smet, Idaho. The airplane was owned and operated by Faunce Ag Aviation Inc., Tekoa, Washington. The commercial pilot, who was the sole occupant, sustained fatal injuries. Visual meteorological conditions prevailed for the flight, which was being operated in accordance with 14 Code of Federal Regulations Part 137, and a flight plan was not filed. The flight departed a private airstrip near Tekoa at about 0700.

According to a witness whose residence was located about 700 ft. east of the accident site, she was watching the pilot spray the field that was located immediately north of and across the road from her house. The pilot was making spray passes in the west and east direction, parallel to a powerline that bordered the south side of the field. The witness stated that she saw the airplane flying south along the west side of the field; the airplane turned left until it was heading east and began a spray pass on the south edge of the field, next to the powerline. The witness reported that, shortly thereafter, she observed downed powerline wires, followed by the sound of the airplane's impact with terrain. The witness stated that she did not see the airplane collide with the wires.

In a telephone interview with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), the owner of the property being sprayed stated that the pilot had been applying a fungicide to the wheat field when the accident occurred. The property owner stated that the pilot had sprayed this field for the past 25 years, that he thought the pilot was very familiar with the environment, and that the pilot had never had any issues while spraying the field in the past.

In an interview with a Federal Aviation Administration (FAA) aviation safety inspector, a family member of the pilot who was familiar with the operation reported that the accident occurred on the pilot's fourth load of the morning. The amount of chemical the pilot departed with was not determined during the investigation.

The pilot held a commercial pilot certificate with an airplane single-engine land rating and a second-class airman medical certificate issued on January 12, 2016, with the following limitations: "Not valid for night flying or by color signal control. Not valid for any class after January 31, 2017."

According to operator-supplied records and the pilot's airman medical application, at the time of the accident, the pilot had accumulated 10,109 hours flight time of which, 7,124 hours were in the accident airplane make and model. The pilot's personal flight logbook was not provided to the IIC during the investigation.

The single-seat, low-wing, fixed-gear, tailwheel-equipped airplane, serial number 1956R, was manufactured in 1974. It was powered by a Garrett TPE331-6-252M engine, serial number P-03069C, rated at 715 horsepower. The most recent annual inspection was performed on November 6, 2015, at a total airframe time of 9,944 hours and an engine total time of 9,888.7 hours. At the time of the accident, the airplane had accumulated a total of 167.1 flight hours since its last inspection.

At 0753, the weather reporting facility at the Pullman/Moscow Regional Airport (PUW), Pullman, Washington, located about 24 nm south of the accident site, reported wind calm, visibility 10 miles, sky clear, temperature 23° C, dew point 13° C, and an altimeter setting of 29.92 inches of mercury.

At the time of the accident, the sun was about 13.8° above the horizon. Additionally, the sun's lateral position was about 20° to the left of the heading of the airplane's eastbound spray run over the field.

View looking east in direction of flight and relative position of sun at time of accident

The single-seat, low-wing, fixed-gear, tailwheel-equipped airplane, serial number 1956R, was manufactured in 1974. It was powered by a Garrett TPE331-6-252M engine, serial number P-03069C, rated at 715 horsepower. The most recent annual inspection was performed on November 6, 2015, at a total airframe time of 9,944 hours and an engine total time of 9,888.7 hours. At the time of the accident, the airplane had accumulated a total of 167.1 flight hours since its last inspection.

On the day following the accident, the NTSB IIC and the FAA inspector surveyed the accident site. Physical evidence showed that the airplane initially impacted a set of guy wires about 660 ft. west of where the airplane entered the field on its spray run: the guy wires were directly in line with and perpendicular to the airplane's flight path. The guy wires were secured to the top of one of the utility poles that supported the powerline bordering the south side of the field. The guy wires descended to the ground on about a 45° angle and were anchored in the field about 65 ft. north of the utility pole. After impacting the guy wires, the airplane collided with and went through the powerline wires, crossed a county road, and impacted a stand of fir trees. The airplane came to rest within the stand of trees about 490 ft. southeast of the initial impact point with the guy wires. An outboard section of the airplane's right wing, about 30 inches in length, was located about 160 ft. east-southeast of the first point of impact with the guy wires. Additionally, yellow and black paint chips, which were consistent with the wing's paint scheme, were located about 100 ft. southeast of the guy wires.

The airplane was severely fragmented and deformed by impact forces. With the exception of about 7 ft. of the inboard section of the forward spar, the right wing was observed separated from the fuselage and destroyed. Additionally, the left wing was observed completely separated from the fuselage and destroyed by impact forces as was the aft fuselage from the cockpit to the forward section of the empennage. The entire empennage separated due to impact forces and was located about 20 ft. south of the main wreckage. The engine remained attached to the fuselage at its mounts. The cockpit was crushed and deformed. With the exception of the outboard section of the right wing, the entire wreckage was located within about a 50-ft radius of the main wreckage site.

No catastrophic mechanical anomalies were noted with the engine or airframe that would have precluded normal operation.

An autopsy was performed on the pilot at the Office of the Medical Examiner, Spokane, Washington. The cause of death was attributed to blunt force trauma.

The FAA's Bioaeronautical Research Laboratory conducted toxicological testing on the pilot. The results were negative for carbon monoxide and ethanol; ibuprofen was detected in cavity blood. Testing for cyanide was not performed.

Ibuprofen is a medication in the nonsteroid anti-inflammatory drug class that is commonly used for treating pain, fever, and inflammation.