N7503HSchweizer Aircraft G-164B · 1990

On June 27, 2023, about 1855 central daylight time, a Schweizer Aircraft Corp G-164B, N7503H, was substantially damaged when it was involved in an accident near Beltrami, Minnesota. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 137 aerial application flight.

The accident occurred near the completion of the pilot’s second aerial application flight to the field and the pilot’s 19th flight of the day. Data extracted from the airplane’s Satloc M3 GPS guidance system showed that the airplane departed at 1825:41, climbed to 1,200 ft msl, and proceeded south to the field. The pilot then descended to about 20 ft above the field and began the first of 12 application runs. On completion of the 12th run, the airplane climbed to about 1,250 ft msl and made two north to south orbits over the east end of the field. On completion of the second orbit, the airplane made a left turn to a heading of about 270o and descended to an altitude of 816 ft msl. The airplane proceeded west across the field from east to west. The last data point recorded by the M3 system showed the airplane at the west edge of the field on a 270o heading, at an altitude of 816 ft, and an airspeed of 134.1 mph. The airplane was discovered in a beet field located about ¼ mile north-northwest of the field that had been sprayed. There were no witnesses to the accident.

Figure 1. GPS Overview of the Accident Flight

Figure 2. Detailed GPS Depiction of Accident Flight

The operator stated that the pilot, on his most recent insurance application, reported having 5,875 total flying hours; 3,158 hours was in the “Ag Cat” powered by a Garrett TPE 331-1-151A turboprop engine, and 944 hours was in an “Ag Cat” powered by a PT-6-A-15 turboprop engine. In the last 90 days, the operator estimated that the pilot had flown about 75 hours in each aircraft type.

The operator described the pilot as responsible, productive, and performed high-quality work. He thought the pilot was in good health and not easily fatigued. The pilot was not married and didn’t appear to have any significant personal life stresses.

On the day of the accident, the pilot began work at 0530 and his first takeoff was about 0600. The operator considered the work required that day to be at a moderate level.

The operator reported that the airplane was carrying 3,020 pounds of product and estimated that there were 45 gallons of Jet-A fuel on board. The operator stated that the pilot flew with that load all the time and there was nothing unusual about it.

The operator reported that the weather was “beautiful” and that it was a “perfect spray day.”

The operator reported that the airplane was carrying 3,020 pounds of product and estimated that there were 45 gallons of Jet-A fuel on board. The operator stated that the pilot flew with that load all the time and there was nothing unusual about it.

The airplane impacted in a beet field near the intersection of two township roads. The airplane came to rest inverted, and the nose was oriented on a southeast heading. The initial impact point consisted of a crater and ground scar that ran about 45 ft on a northwest heading to the airplane. Ground impressions from both top wings were located on each side of the ground scar about 20 ft from the initial impact point, indicating the airplane impacted the ground in an upright wings-level, nose-down attitude (see Figure 3) and then nosed over. The airplane’s underbelly components, including the spray pump, were located at the initial impact point. Small pieces of metal and yellow paint chips were found along the ground scar leading from the initial impact point northwest to the airplane main wreckage.

Figure 3. Overhead View of the Accident Scene (Source: Polk County, Minnesota, Sheriff)

The main wreckage contained all the airplane’s major components. The top of the fuselage and the vertical stabilizer and rudder were crushed downward. The upper wing was bent forward with the top wing skin crushed downward. The bottom left wing was broken forward at the wing root. The bottom right wing remained intact and showed skin buckling. Both main landing gear were broken aft. The engine was intact and the mounts were bent downward. The cowling was bent and crushed downward around the engine. The three-bladed propeller remained attached to the engine flange. The spinner was attached to the propeller hub and was crushed inward and torn on one side. One propeller blade was bent about 100° aft approximately 12-inches outboard of the hub. The second blade was bent aft slightly at the hub and twisted aft. The blade tip was fractured longitudinally and separated. The third blade was bent forward at mid-span and twisted. The blade face near the tip showed chordwise scratches.

Figure 4. Airplane Wreckage

Fuel was observed on the ground at the accident site; fuel that was drained had no indications of water or sediment.

An examination of the airplane’s flight control system at the accident site showed no preaccident failures or malfunctions that would have precluded normal operation.

The airplane was recovered to a salvage facility for further examination. The airplane’s SATLOC system devices, cockpit engine instruments, and a Garmin aera 560 were removed from the airplane and sent to the National Transportation Safety Board (NTSB) Vehicle Recorders Laboratory for further examination and data download. The engine, propeller, and propeller governor were sent to the manufacturers for further examination.

Postaccident examination of the airplane’s engine revealed that the ring gear hub and torsional shaft showed fracture features indicative of torsional overload. The propeller governor showed no preaccident signs of abnormal operation.

Further examination of the propeller showed that all three blades exhibited chordwise-rotational abrasion, primarily on the camber side and varying degrees of leading edge nicks and bends. One blade was bent forward in the thrust direction and two were bent aft. All three blades exhibited compound bending and twisting with remarkable bending opposite rotation. Witness marks on the interior piston cylinder wall from contact with the piston shoulder equated to a propeller blade angle from 9.6o and 14.7o, which were within the normal operating range of 6o and 27o.

Components sent to the NTSB Vehicle Recorders Laboratory were examined and, where data was available, were downloaded. Detailed observations with respect to each examined component can be found in the NTSB Multiple Electronics Devices Specialist’s Factual Report in the public docket for this case.

Data retrieved from the airplane’s Satloc M3 system showed heading, altitude, and groundspeed parameters from the accident flight and the previous flight.

An Electronics International OPT-1 Oil Temperature and Pressure gauge recorded oil temperature and pressure history for the accident flight.

An Electronics International M-1 Turbin Outlet Temperature (TOT) gauge recorded the engine turbine’s outlet temperature history for the accident flight.

An Electronics International R-1 N-1 gauge is a digital tachometer that is capable of tracking total flight and tachometer time. The device also records a limited amount of rpm history. The device recorded the tach time and most recent flight history in hours and minutes but did not record any valid rpm history.

An Electronics International FP-5 Fuel Indicator device designed to provide fuel management information to the pilot did not contain any data pertinent to the accident flight.

An Electronics international VA-1A-300 gauge used to monitor electric voltage and current of the circuitry on the airplane did not have any recording capability; therefore, no data pertinent to the accident was recovered from the device.

An autopsy of the pilot was performed by the University of North Dakota Forensic Pathology School of Medicine and Health Sciences. The cause of death was determined as blunt force trauma.

The Federal Aviation Administration Civil Aerospace Medical Institute Bioaeronautical Sciences Research Branch, Forensic Sciences, performed toxicology testing of postmortem specimens from the pilot. The results were negative for all tests conducted.