History of Flight
On April 8, 2009, at 1439 central daylight time, a Cessna 337C, registration N2489S, operated by the Wisconsin Department of Natural Resources (DNR), impacted an agricultural field while responding to a ground fire. Visual meteorological conditions prevailed. The airplane was being operated as a public-use aircraft. The pilot, the sole occupant, was fatally injured. The flight departed from Necedah Airport, Necedah, Wisconsin, at 1411.
The Rack Township Fire Department responded to a ground fire that started from a burn barrel at a residence north of the field. A wooded area separated the residence and the field. The Fire Department Deputy Chief observed the airplane at an altitude he described as "several thousand" feet above ground level and in the "stratosphere." He then walked to a point about 100 feet north of the main wreckage. From there, he saw the airplane circle three times while descending. He did not hear a decrease in engine noise during the descent. During the third circle, the airplane flew south at an altitude he thought "seemed low," about 100 feet above the trees. About 15 seconds before the accident, the airplane continued south while banking left 30-45 degrees. It was about 150 yards from the tree line when it turned north. The airplane descended and rolled to an almost wings-level attitude on a northerly heading approaching the tree line at about 35 feet above ground. He then heard the engine noise increase about 5 seconds prior to the left wing dropping, and the airplane descended and impacted the ground. He noted that the landing gear was retracted and no lights were illuminated.
The Pittsville Fire Department Chief reported seeing the airplane at an altitude about 1.5 to 2 times the height of the trees. The airplane descended at a "sharp angle" during the third circle, and the engine was running.
Personnel Information
The pilot held an airline transport pilot certificate with multiengine and commercial single-engine land ratings, and a flight instructor certificate. As of April 8, 2009, he had accumulated 4,739.1 total flight hours. He served as a DNR pilot and received a Cessna 337 initial flight check on April 3, 2009, lasting 1.0 hours. He subsequently flew 3.1 hours in the accident airplane on April 7 and April 8, 2009. FAA records showed no reported incidents, accidents, or enforcement actions. He was issued a first-class medical certificate on February 25, 2009, with no limitations.
Aircraft Information
The 1967 Cessna 337C was operating as a public-use aircraft as of January 7, 2009, with a Hobbs time of 205.3 hours. It was used for aerial observations. It was powered by two Continental IO-360-CB engines. The airframe and engines received their last annual inspections on September 15, 2008, at an aircraft total time of 2,530.0 hours. The airplane was equipped with Horton STOL kits under supplemental type certificates (STCs) SA937CE and SA2821CE, and a BAS, Inc. shoulder harness system under STC SA2067NM.
Wreckage and Impact Information
The main wreckage was located at 44°28.705'N, 90°16.690'W, elevation 1,094 feet, in a fallow wheat field. The fuselage was upright with a heading of about 240 degrees. The left wing displayed more wrinkling and damage than the right. Both wings were attached but fractured at the wing strut attachment. The stall fence on the left wing was separated and deformed. The wing flap jackscrew indicated 10 degrees of flap extension, consistent with the cockpit switch position. Flight control continuity was confirmed. The landing gear was retracted. The front engine propeller had separated; one blade showed overload fracture, bending, and twisting. The rear engine propeller was attached with twisting on one blade. Both engines rotated by hand and produced spark from magnetos. Fuel pumps operated and discharged fuel. Oil drained from both engines; the front oil filter and rear oil screen were unobstructed. Fuel manifold valve screens and injectors were clear. First responders reported fuel smell, and fuel spilled from the right wing during recovery.
Medical Information
An autopsy conducted on April 10, 2009, reported multiple blunt force injuries, no significant disease, no ethanol detected, and negative drug screen results. The FAA's final forensic toxicology report was negative for all substances tested.
Fire
The ground fire originated from a garbage fire near a house at 44°28.796'N, 90°16.762'W, elevation 1,117 feet. There was no evidence of soot or fire on the airplane except a small area by the front engine left cowl flap. A small flame at the bottom of the fuselage was extinguished by first responders.
Test and Research
The accident airplane and two other DNR aircraft were equipped with Horton STOL kit installations. No additional placards or airspeed markings were present, and no STC supplements provided quantitative performance data. The STC instructions stated the aircraft could be operated as per the Cessna handbook, but pilots should familiarize themselves at a safe altitude. A questionnaire completed by the pilot listed VS0 as 66 and VS1 as 75 mph, while the flight manual listed stall speeds of 67 mph CAS (gear down, flaps down) and 78 mph CAS (gear and flaps up). A DNR representative stated that aircraft are flown single-pilot for observations, often near stall speed with intermittent stall warning, and that the airspeed and configuration for observation flights in the Cessna 337C are 95 mph indicated with 10 degrees of flaps. There is no minimum altitude; the DNR has a low altitude waiver from the FAA applicable to parts 91.119(b), (c) and 91.313(3). The aircraft's status was changed from Part 91 to public-use by the accident pilot on January 7, 2009.