N524SLAyres S2R-T34 · 1994

On July 28, 2025, about 1537 central daylight time, an Ayres Corporation S2R-T34 airplane, N524SL, sustained substantial damage when it was involved in an accident near Akron, Iowa. The pilot sustained serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 137 agricultural flight.

The purpose of the low-level aerial application flight was to apply liquid chemical to a field of corn in a rural area. The airplane departed from the Sioux County Regional Airport (SXK), Maurice, Iowa, about 1456. After the completion of the aerial application work, the intent was to return to SXK. At the time of departure, the airplane had about 175 gallons of Jet A fuel on board and about 422 gallons of a mixture of AccuDrop, Aproach Prima, and Lamda-CY AG in the hopper. When the airplane arrived at the field, the pilot maneuvered the airplane for two reconnaissance passes, to identify any obstacles, wires, and sensitive areas to avoid.

After verifying the engine power settings, he began the aerial application work. After several spray passes, the pilot maneuvered the airplane to turn for another spray pass to the north, when the engine sustained a total loss of power. The pilot reported the total loss of engine power occurred about 70 ft above ground level, and the engine “sounded like it exploded.” Prior to the total loss of power, there were no indications of abnormal performance from the engine.

The pilot immediately brought the airplane to a level attitude and began to troubleshoot the emergency. The pilot quickly scanned the cockpit instruments and observed the torque (TQ) indication was below 30 psi and the inter-turbine temperature (ITT) indication was well below 700° Celsius. The pilot pushed the propeller lever forward to obtain a response from power lever inputs. No response was received, so he pulled the propeller lever to the feather position, and he felt the airplane begin to glide.

Directly in the airplane’s flight path was a house and a church, so the pilot decided not to perform an emergency hopper dump to prevent possible chemical exposure to any ground personnel. Additionally, beyond the house and church, the concern was that if an emergency hopper dump was performed, the resulting increase in altitude may cause the airplane to land near other homes, farm buildings, and wires on the other side of the field. The pilot reported the decision not to perform an emergency hopper dump was a calculated decision to avoid injury to ground personnel and to avoid damage to property.

The pilot maneuvered the airplane to a nearby soybean field to perform the forced landing. The pilot was able to land the airplane to the field. During the landing roll, the main landing gear dug into the wet ground and the airplane nosed over. The pilot released himself from the 4-point restraint system he was utilizing and egressed from the inverted airplane via the fractured left window. The pilot then walked to a nearby home for assistance.

The airplane sustained substantial damage to both wings, the fuselage, and the empennage. The airplane was recovered from the accident site, and it was transported to a secure location for future examination.

The pilot was utilizing an airplane flight helmet with a visor, and he reported that the sun did not interfere with his vision during the forced landing. Additionally, he reported that he did not feel fatigued during the accident flight.

Prior to the accident occurring, the pilot reported there were no known issues with the airplane. On May 15, 2025, at a total of 1,073.1 hours since overhaul, the engine had an annual inspection performed by a mechanic. On May 16, 2025, at a total of 13,268.4 airframe hours, the airframe had an annual inspection performed by a mechanic.

The operator, Crop Dusters LLC, based at SXK, utilizes a fleet of Ayres Corporation S2R series airplanes for aerial application work.

The airplane, known as a Turbo Thrush, was manufactured in 1994 and has a 500-gallon capacity hopper. The airplane is a dual cockpit configuration, with two tandem seats. The Federal Aviation Administration (FAA) Type Certificate for the airplane, A4SW, is currently held by Thrush Aircraft, LLC, Albany, Georgia. The airplane was equipped with a Pratt & Whitney Canada PT6A-34AG turboprop engine. The airplane was also equipped with a Hartzell Propeller HC-B4TN-3C/T10702NS four-blade controllable pitch aluminum propeller.

The FAA-approved airplane flight manual discusses the indications of an engine flameout and states in part:

The indications of an engine flameout will be a drop in the inter-turbine temperature, a drop in the torque pressure, and a drop in RPM. The flameout may result from the engine running out of fuel or possibly caused by an unstable engine operation.

The calculated density altitude for the closest meteorological reporting station was 3,615 ft.

On July 9, 2015, about 1050 eastern daylight time, N524SL, an Ayres Corporation S2R T34, was substantially damaged during a forced landing immediately after takeoff from a private airstrip near Climax, Georgia. The commercial pilot was not injured. The airplane was registered to and operated by a private company. Visual meteorological conditions prevailed and no flight plan was filed for the aerial application flight that was being conducted under the provisions of 14 Code of Federal Regulations Part 137.The pilot stated that the accident flight was his third flight of the day and the two previous flights were uneventful. The wind was calm and he taxied to the west end of the 1,900 foot-long grass runway for a departure to the east. As the pilot prepared to takeoff, he brought the power up and checked the engine gauges. He said everything was normal and he proceeded to depart. When the airplane became airborne it "quickly settled to the ground as if the prop quit pulling." The pilot said there were no unusual engine noises or vibrations and the engine stayed running, but the propeller stopped producing thrust "like it was wind milling." The airplane struck a wire fence and came to rest in a cornfield at the end of the runway. The pilot said that his hand was on the power-lever the entire flight and he never moved the propeller control, which was full forward. He said the engine continued to run at takeoff power for about 30-to 45 seconds before he was able to shut it down.

An initial postaccident examination of the airplane and engine by a Federal Aviation Administration (FAA) inspector and Pratt &Whitney Field Service Representative revealed the left and right wing spars were substantially damaged. The propeller, firewall, landing gear, and lower fuselage were also damaged. The engine's power section was seized and would not rotate, but the gas generator compressor would turn through the AGB starter pad. The main engine oil filter was removed and no debris was noted. The power section chip detector and strainer were removed and no debris was noted. The PY and P3 sense lines were visually inspected and found to be in good condition. Positive torque was applied to all "B" nuts for the PY and P3 sense lines and all nuts were secure. The left exhaust stack was removed for power turbine blade inspection and found to be intact and in good condition. The power section rotor could not rotate. The airframe fuel filter was removed and the bowl was full of fuel and absent of debris and water.

The turbo-prop engine (Model PT6A-34, S/N 56452) was sent to Pratt & Whitney Canada where an examination and engine test-run were conducted under the supervision of the Canadian Transportation Safety Board (TSB). The engine power section displayed contact signatures consistent with the engine being near a high power setting at the time of impact. The engine was test-run using a slave power section, the original propeller governor assembly and a slave P3 filter and housing. The first attempt to start the engine resulted in a hung start. All pneumatic lines were checked and the P3 filter was checked with no anomalies found. The second start attempt again resulted in a hung start. Installation of a slave fuel control unit resulted in a normal start and test-run of the engine. Bench testing of the fuel control showed normal operation, and disassembly and detail inspection showed all the internal components to be in normal condition. The cause of the hung starts could not be determined.

The engine's last 100-hour inspection was conducted on June 18, 2015, and it had accrued 27,561 hours since new and 6,119.9 hours since overhaul. No pre-mishap mechanical discrepancies were noted with the engine or its components that would have precluded normal engine operation prior to impact.

The three-blade propeller (Model HC-B3TN-3D, S/N BUA32424) was examined on August 6, 2015 at the operator's facility, and additional examination of the propeller's cylinder assembly was conducted at Hartzell Propeller Inc. on October 5, 2015, under the supervision of the FAA. The propeller assembly remained attached to the engine and all three blades were uniformly twisted and bent aft toward low pitch. The cylinder, piston, feathering spring assembly and guide collar had separated from the hub unit but remained attached to the propeller assembly by the link arms and beta rods. The propeller assembly was removed and the interior of the piston was examined. An impact mark was observed about 2-inches from the bottom edge of the piston near the No. 2 blade. According to Hartzell, this equated to a blade angle about 12 degrees (toward flight idle) and that the piston was extended toward low pitch during the impact sequence. The piston also exhibited impact marks from the propeller's counterweight arms/slugs. The guide collar was fractured and marks were observed near each of the propeller blade's respective link arms. All three of the link arms were bent but remained secure to their respective attachment point. The No. 2 link arm was fractured. The cylinder, which had separated during the impact sequence, exhibited damage to the attachment threads. To determine if the cylinder may have separated due to a material anomaly with the thread, it was sent to Hartzell for additional testing. The testing revealed no material anomalies.

The propeller's last 100-hour inspection was conducted on June 18, 2015, and it had accrued 591.1 hours since overhaul.

The pilot held a commercial pilot certificate with a rating for airplane single-engine land. He reported a total of 6,986.8 hours; of which, 2,000 hours were in the same make/model as the accident airplane. His last FAA second class medical certificate was issued on April 22, 2015.

Weather reported at Camilla-Mitchell County Airport, Camilla, Georgia, about 12 miles northeast of the accident site, at 1000, included variable wind from 4 knots gusting to 6 knots, visibility 10 miles, clear skies and temperature of 90 degrees F.