Accident Overview
On June 20, 2024, at approximately 0706 eastern daylight time, an Ayres Corporation S2R-600 airplane, registration N4004K, sustained substantial damage during an accident near Stanwood, Michigan. The commercial pilot, who was the sole occupant, was uninjured. The airplane was being operated as a Title 14 Code of Federal Regulations Part 137 aerial application flight.
Flight Details
The flight was intended to apply agricultural fungicide to a potato field in a rural area. The airplane had departed earlier that morning from the operator’s facility at Lakeview Airport (13C) in Lakeview, Michigan. During the application, the airplane was flying westward at about 130 mph approximately 10 ft above ground level.
Events Leading to the Accident
After completing the chemical application, the pilot momentarily turned his head and body to the left to view the spray boom pressure gauge, which was located outside the cockpit. Shortly after looking at the gauge, the main landing gear impacted terrain. The pilot immediately pulled up to gain altitude. The impact forced the left main landing gear upward into the left wing, causing fuel to leak from the left wing fuel tank.
Emergency Landing
The pilot executed a forced landing to a flat grass field. During the landing, the airplane came to rest upright on its nose and forward fuselage. The pilot performed an emergency shutdown and egressed without further incident.
Damage and Mechanical Status
The airplane sustained substantial damage to the fuselage and both wings. The pilot reported no preimpact mechanical malfunctions or failures with the airframe or engine that would have precluded normal operation.
Pilot Actions and Equipment
The pilot, who was wearing a flight helmet with a visor, reported that he did not feel fatigued during the flight. To view the spray boom pressure gauge—mounted on the left spray boom at about the 8 o’clock position relative to the cockpit—he needed to look left and down. The pilot estimated it took one to two seconds to read the analog gauge due to its distance from the cockpit, about 8 ft. He noted that he could partially turn and view the gauge while using the four-point restraint system.
Aircraft Configuration and Operator Practices
The airplane was equipped with an Electronics International MVP-50T engine monitor system, but it was not configured to display spray boom pressure. The pilot, who also held a mechanic certificate, described the gauge location as a “bad design.” The operator reported that all five of its Thrush S2R series airplanes had the spray boom pressure gauge mounted on the left side spray boom, as that location was believed to provide the most reliable reading.
Regulatory and Manufacturer Information
A review of the FAA Type Certificate Data Sheet A4SW (revision 44) and FAA Advisory Circular 137-1B revealed no guidance on the location of the spray boom pressure gauge. According to Thrush Aircraft, airplanes manufactured since 2012 are equipped with an MVP-50T system configured to show spray boom pressure. No relevant service bulletins or service letters addressing gauge location were found. The Thrush Aircraft Illustrated Parts Catalog for the S2R model showed the gauge on the instrument panel, while the installation drawing 80809-9 showed it outside the cockpit, forward of the windshield on the hopper, within the pilot's forward line of sight.
Operator Modifications
The operator reported that when the airplane was purchased, it lacked a spray boom system and an in-cockpit pressure gauge. The operator installed and configured the current spray boom system using components from another aerial application airplane.
Previous Similar Occurrence
In 2003, an Ayres S2R-T660 (serial number T660-102) was destroyed after impacting transmission wires during a low-level spray run (NTSB accident number CHI03LA273). The pilot, who sustained minor injuries, stated that he had looked down to check the spray boom pressure gauge and when he looked up, the wires were in his face.