Incident Summary
On 16 December 2011 at approximately 0700Z, an Air Tractor AT-602, registration ZS-NZW, was involved in an incident during a crop spraying operation on Farm Theunissen near Parys, Free State, South Africa. The pilot, who held a valid commercial pilot's license and agricultural rating, reported that the engine failed while performing a left turn during the transfer of fuel from the left to the right wing tank. The aircraft was at an altitude of about 200 feet when the engine stalled. The pilot executed a forced landing in a nearby cornfield, dumping the remaining crop-spraying chemical before touchdown.
Aircraft and Pilot Information
The aircraft was an Air Tractor AT-602 (serial number 602-0424, manufactured 13 May 1977) owned by FFA Assets (Pty) Ltd. It was powered by a Pratt & Whitney Canada engine (serial number PCE-PN0009) and fitted with a Hartzell propeller (serial number EVA2115). At the time of the incident, the airframe had accumulated 1,451 hours. The last maintenance performed was on 23 November 2011 at 1,427.5 hours. The pilot was 58 years old with 7,348.15 total flying hours, including 594.30 hours on type. The flight was conducted under Part 137 restricted category operations.
Sequence of Events
The pilot began crop spraying with a full fuel tank, estimating a three-hour endurance. On the last takeoff, the fuel gauge indicated approximately 250 liters remaining, which was confirmed by a dipstick test. Shortly after takeoff, while in a left turn and simultaneously transferring fuel from the left to right tank, the engine stalled. The pilot initiated a forced landing on a cornfield ahead. Upon touchdown, the landing gear wheels sank into a furrow in the soft ploughed ground, causing the aircraft to nose forward and the propeller to strike the ground. The aircraft came to rest in a three-point attitude with the tail wheel and main landing gear on the ground. The pilot was not injured.
Damage and Injuries
The aircraft sustained minor damage to the propeller (blades bent) and engine. No other damage was reported. The pilot, who was the sole occupant, was properly restrained and did not sustain any injuries. No pre- or post-impact fire occurred.
Meteorological Conditions
Weather information obtained from the pilot indicated wind from 315° at 2 knots, visibility CAVOK, temperature 20°C, and clear skies. Weather was not considered a factor in the incident.
Probable Cause and Contributory Factors
The incident report stated the probable cause as an unsuccessful forced landing. A contributory factor was fuel starvation.
Additional Information
The manufacturer had distributed Service Letter #178 regarding fuel starvation in Air Tractor aircraft, and the pilot was aware of it. The aircraft was operating from a private runway on the farm, outside controlled airspace, and no ATC communication was involved.