Accident Overview
On June 3, 2023, about 1158 central daylight time, an Air Tractor AT-502B airplane, registration N509HB, sustained substantial damage during an accident near Lake Village, Arkansas. The pilot was not injured. The flight was conducted under Title 14 Code of Federal Regulations Part 137 as an aerial application operation.
Sequence of Events
According to the pilot, shortly after departure the airplane experienced a loss of thrust as the propeller moved toward a feathered position, though the engine continued operating. Unable to maintain flight with reduced thrust, the pilot jettisoned fertilizer and executed a forced landing to a field. The impact resulted in substantial damage to the fuselage, empennage, and both wings.
Maintenance and Examination
Maintenance records indicate that the airplane received maintenance the preceding day at a Part 145 repair station. That work included an adjustment to the propeller beta plunger, but the extent of work was not documented on the work order or in the logbook. Postaccident examination established continuity of engine and propeller controls from cockpit to components, with no anomalies. The propeller blades were bent aft opposite rotation with chordwise scoring and abrasion, consistent with high impact forces at low power and low blade pitch angle. The beta system operated smoothly when tested. The engine showed contact signatures on power turbine blades and vane ring indicating power development at impact, and no preimpact mechanical anomalies were found. The fuel control unit, fuel oil heat exchanger, and fuel pump were analyzed by Pratt & Whitney Canada, which found no preimpact issues.
Fuel and Weight Considerations
The fuel quantity at the time of the accident could not be definitively determined. An FAA inspector found no visible fuel in the wing tanks, which were neither compromised nor leaking, and no fuel odor or ground staining. The pilot and operator stated no fuel was removed before the inspector arrived. A weight and balance sheet from 2008 listed empty weight at 4,790.5 lbs. The hopper held 2,900 lbs of fertilizer, and the pilot estimated about 120 gallons of fuel (3/4 tanks). Based on available data, the airplane’s weight was estimated at or over 8,000 lbs. The Air Tractor Flight Manual specifies flap settings: for takeoff weight under 8,000 lbs, flaps set to 10°; over 8,000 lbs, flaps set to 20°. Accident scene photographs showed flaps set to about 20°.
Weather and Performance
Weather recorded at Mid Delta Regional Airport, about 20 miles northeast, at 1153 was: wind 060° at 4 knots, clear skies, 10 statute miles visibility, temperature 31.1°C, dew point 18.9°C, altimeter 29.85 inHg, density altitude 2,377 ft. The pilot departed south. Performance estimates using minimum 8,000 lbs and maximum 9,400 lbs indicated takeoff ground roll on a paved runway between 1,418 ft and 2,156 ft. The departure airstrip was about 2,100 ft of paved surface. Unpaved surfaces, high density altitude, and tailwinds would increase ground roll distance.
Regulatory Guidance
The FAA Pilot's Handbook of Aeronautical Knowledge notes that density altitude affects airplane performance, and tailwinds can significantly increase takeoff distance.
Conclusion
The investigation determined no evidence of preimpact mechanical malfunction or failure. No probable cause was stated.