N2249BAyres S2R-T34 · 1997

On May 30, 2018, about 1710 central daylight time, an Ayres Corporation S2R-T34 airplane, N2249B, impacted guy wires and terrain near El Reno, Oklahoma. The commercial pilot was fatally injured, and the airplane was destroyed by postimpact fire. The airplane was registered to Ag Aviation Equipment LLC and operated by Andy Deterding Ag Aviation as a Title 14 Code of Federal Regulations Part 137 aerial application flight. Day visual meteorological conditions prevailed in the area, and no flight plan was filed for the flight, which originated at Medford Municipal Airport (O53), Medford, Oklahoma, about 1600.

Two witnesses stated that, just after 1700, they heard an airplane flying low over their house. They stepped outside to watch the airplane fly over the field about 1/2 mile to the north. One of the witnesses noticed the airplane make a tight turn, as if the pilot was attempting to avoid the radio tower guy wire, and it appeared that the pilot "was pulling up." He then saw the airplane's nose pitch up and immediately "go towards the ground."

According to the pilot's son, who was the operator's chief pilot, the pilot began flying in the late morning, between 0900 and 0930, on the day of the accident. The pilot took a 1-hour break for lunch about 1300 and continued to fly after lunch. The pilot departed to fly his last load to El Reno about 1600. The airplane had a full fuel load, so the flight had a "light load" of chemical. The tower was depicted on the map of the field the pilot had with him for spraying operations, and the pilot's son stated the pilot had flown aerial application flights over that field for several years. The pilot was expected to return to a grass strip in Carrier, Oklahoma, to reload if time permitted. Usually, the pilot would fly until about 1900, approximately 2 hours before dark, before ending flights for the day; it was typical for the pilot to fly all day.

The pilot held a commercial pilot certificate with an airplane single-engine land rating. According to information provided on his most recent Federal Aviation Administration (FAA) second-class medical certificate application, as of March 5, 2018, the pilot had about 1,500 total hours of flight experience, with 250 hours in the previous 6 months. The medical certificate was issued with a limitation for corrective lenses.

The yellow, single-seat, low-wing, fixed-gear airplane was manufactured in 1997 and was designed for aerial agricultural application. It was powered by a Pratt and Whitney model PT6A-34AG turboprop engine, serial number PH1063, and equipped with an Hartzell HC-B3TN-3D/T10282N+4 four-bladed propeller.

The most recent annual inspection was completed on April 3, 2018, at 6,843.4 hours total airframe time. The engine was installed as factory new on April 3, 2018, with 0 time at installation. Maintenance records indicated a final inspection and engine run were completed on the engine before returning the airplane to service after completion of the annual inspection.

The 1555 recorded weather observation at Clarence E. Page Municipal Airport (RCE),Oklahoma City, Oklahoma, located 8 miles south-southeast of the accident site, included wind from 140º at 12 kts, 10 miles visibility, few clouds at 5,500 ft, temperature 35ºC, dew point 21ºC; barometric altimeter 29.70 inches of mercury.

The National Oceanic and Atmospheric Administration solar position calculator indicated that, at 1710, the position of the sun in Oklahoma City, Oklahoma, was at an altitude of 40.07º and an azimuth of 269.89º. The airplane was flying from west to east at the time of the accident.

The yellow, single-seat, low-wing, fixed-gear airplane was manufactured in 1997 and was designed for aerial agricultural application. It was powered by a Pratt and Whitney model PT6A-34AG turboprop engine, serial number PH1063, and equipped with an Hartzell HC-B3TN-3D/T10282N+4 four-bladed propeller.

The most recent annual inspection was completed on April 3, 2018, at 6,843.4 hours total airframe time. The engine was installed as factory new on April 3, 2018, with 0 time at installation. Maintenance records indicated a final inspection and engine run were completed on the engine before returning the airplane to service after completion of the annual inspection.

The airplane impacted the ground about 200 feet east of the wires at the edge of a ravine and came to rest inverted. The nose section, fuselage, empennage, and landing gear were consumed by postcrash fire. About 1 ft of the outboard section of a propeller blade was missing and was found in the field north of the main wreckage. A piece of the lower section of cowling and adjoining air scoop displayed damage consistent with impacting the guy wire. Both pieces were detached from the remainder of the wreckage and were lying in the field, closest to the fallen guy wires.

About 25% of the outboard section of the left wing was not fire damaged and exhibited impact damage with significant leading edge and wingtip crushing along the wingspan. The right wing exhibited thermal damage to about half of the inboard section with significant leading edge crushing along the wingspan. Flight control continuity was established from all flight control surfaces to the cockpit area. Continuity to the control stick could not be verified due to the extensive thermal damage to the cockpit.

The propeller assembly and the engine were impact separated from the airplane. The propeller blades displayed varying degrees of bending, one fractured tip, and impact damage. The exhaust duct displayed compression bending due to contact with guy wires and impact with terrain. The exhaust duct also displayed some evidence of torsional bending. The exhaust stacks were bent and distorted. The left stack was impact separated from the exhaust duct. The gas generator case was bent and distorted. The engine was separated at the "C" flange to expose the hot section components. The downstream face of the compressor turbine disc and blades exhibited rotational scoring from contact with its respective adjacent static components. The upstream face of the compressor turbine blades exhibited scoring from contact with the compressor turbine vane. The power turbine vane baffle was separated from the power turbine vane. The baffle exhibited rubbing on both sides from contact with the power turbine and compressor turbine discs and blades. The power turbine disc and blades exhibited rotational scoring on the upstream face. Several blades were fractured. The oil filter cover was removed. Dark and partially burnt oil was evident adjacent to the filter. The end cap of the filter was removed during the attempted removal of the filter. The reduction gearbox magnetic chip detector was thermally damaged from the post-impact fire, which melted the rubber material covering the magnetic poles. The inlet screen was sectioned to view the first stage compressor blades through the inlet case struts. The visible first stage compressor blades were coated with soot from the post-impact fire. The visible blades did not exhibit any impact damage.

The propeller blade bending, rotational scoring on the compressor turbine disc/blades, and the rotational scoring on the power turbine disc/blades was consistent with the engine producing power at the time of impact.

The top and middle guy wires displayed yellow paint transfers at about the 155-ft mark on the wire, as measured from the ground attachment point toward the tower attachment. Based on the location of paint transfer on the top wire and the attachment height of the wire to the tower, the airplane's estimated altitude at the time of the wire strike was about 125 ft above ground level.

The State of Oklahoma, Office of the Chief Medical Examiner, Oklahoma City, Oklahoma, performed an autopsy of the pilot. The cause of death was multiple blunt force injuries. The autopsy revealed an enlarged heart and severe atherosclerotic disease of one coronary artery with greater than 80% narrowing of the proximal right coronary artery. There was mild to moderate disease of the left anterior descending coronary artery, and a poorly defined area of myocardial fibrosis on the left ventricular free wall. No other significant natural disease was identified.

Toxicology testing performed by the FAA's Forensic Sciences Laboratory identified ibuprofen in urine; verapamil in blood and urine; norverapamil in blood and urine; and rosuvastatin in urine.

Verapamil (of which norverapamil is a metabolite) is used to treat high blood pressure. Rosuvastatin is a prescription medication used to reduce blood cholesterol and triglycerides levels. Neither medication is considered to pose a hazard to flight safety.