Background
On June 6, 2013, about 1930 mountain daylight time, a Weatherly 620B airplane, registration N350WR, was substantially damaged when it impacted terrain near Ludlow, South Dakota. A postimpact fire ensued. The commercial pilot was fatally injured. The airplane was registered to and operated by Air Kraft Spraying Inc., operating under 14 CFR Part 137 as an aerial application flight. Visual meteorological conditions prevailed, and the flight operated without a flight plan. The local flight originated from a private airstrip near Ludlow around 1830.
Pilot Information
The 39-year-old pilot held a commercial pilot certificate with an airplane single-engine land rating issued June 5, 2012, with a limitation restricting carriage of persons for hire in cross-country flights beyond 50 nautical miles or at night. He held a second-class medical certificate issued January 15, 2013, without limitations. His logbook showed at least 752.3 total flight hours, including 76 hours in the accident make and model. He had logged 465 hours of agricultural experience in the 2012 season. No logbook entries reflected flight time after April 12, 2013. He completed a flight review on June 5, 2012, and had an undated endorsement for Part 137.19(c) knowledge and skills demonstration. He had not attended formal agricultural flight training; his experience was on-the-job. He attended the 2013 PAASS training and held a South Dakota chemical applicator license.
Aircraft Information
The accident airplane, a Weatherly Aviation Company 620B (serial number 1612), manufactured in 1996, held an FAA restricted airworthiness certificate for agricultural and pest control. It was powered by a Pratt & Whitney R-985-AN-14B engine rated at 450 horsepower, equipped with a Hartzell three-blade propeller. The airplane was maintained under an annual inspection program; the last annual inspection was completed May 20, 2013, at an airframe total time of 3,146 hours. The Weatherly 620B is not equipped with flaps.
Accident Details
Colleagues reported the pilot was applying pesticide and insecticide to a wheat-grass field adjacent to the crash site. A map of the 891.72-acre field showed the southern boundary delineated by Highway 858, with the remainder defined by fences and property boundaries. The wreckage was located between the north and south boundaries. According to colleagues, in that area the pilot should have been in straight and level flight following a north/south application path, not maneuvering. A local resident south of the accident site observed the airplane making multiple passes, then lost sight and saw smoke minutes later.
Meteorological Information
The closest official weather station was Hettinger Municipal Airport (KHEI), 45 nautical miles northeast of the accident site, elevation 2,706 feet msl. The 1853 METAR reported calm wind, 10 miles visibility, clear sky, temperature 19°C, dew point 6°C, altimeter 30.03 inches. Calculated density altitude was 4,094 feet.
Wreckage and Impact
The accident site was in rolling terrain with short grass, elevation 2,946 feet msl. The airplane impacted on a magnetic heading of 180°. Initial impact marks included two deep ground scars 12 inches apart consistent with propeller strikes. The engine and propeller assembly separated from the main wreckage. The engine was horizontal in a ground scar, impact-damaged, with dirt embedded. Two of three propeller blades remained attached; blade B was bowed aft and twisted, blade C separated and was found in a crater. Two long, narrow ground scars extended east and west from a center scar, containing paint chips and plexiglass consistent with wing leading edges. A burn area extended 107 feet south and west of the main wreckage. The main wreckage included both wings, fuselage, and empennage. The fuselage cabin and instrument panel were charred, melted, and partially consumed by fire. Left wing leading edge had accordion crushing; right wing was charred and melted. Aileron control continuity could not be established due to fire damage. Elevator control tubes were continuous aft of the fuselage but continuity forward could not be established due to fire damage. Rudder control cables were continuous to the rudder pedals. No preaccident mechanical malfunctions or failures were found that would have precluded normal operation.
Additional Information
Colleagues stated the pilot woke around 0700, slept 7-8 hours, and began spraying at 0930 due to fog. He flew all morning, took a 10-15 minute lunch break around 1300, then flew until the accident, estimated 9 total flight hours that day. They were unaware of other breaks or exact number of loads.
Medical and Pathological Information
An autopsy performed June 10, 2013, concluded the cause of death was blunt trauma injuries from the accident. Toxicological tests by the FAA's Civil Aerospace Medical Institute detected salicylate in urine; tests for carbon monoxide and ethanol were negative; cyanide tests were not performed.
Engine Examination
The engine was examined post-accident. Spark plugs from the forward bank were removed; four were sedimented from the postimpact environment, others showed normal wear signatures. Cylinders, pushrods, and journals had impact damage. Cylinders had carbon deposits on intake valves and corrosion on exhaust valves. Oil was clean; oil filter and chip plug were unremarkable. Throttle and mixture linkages were attached but impact damaged. Carburetor fuel screen was clean. Magnetos and propeller governor were impact damaged and not functionally testable. No mechanical anomalies precluding normal operation were found.