Accident Details
On April 21, 2010, at approximately 1815 central daylight time, an Air Tractor AT-802A, registration N9197F, operated by Aero Tech, Inc., of Clovis, New Mexico, was substantially damaged when its engine lost power. The pilot performed an off-airport landing in a field located 20 miles south of Alpine, Texas. Visual meteorological conditions prevailed at the time. The flight was conducted under 14 CFR Part 137 without a flight plan. The pilot, who was uninjured, had originated the local flight from Alpine-Casparis Municipal Airport (E38) around 1610.
Pilot Account
According to the pilot's accident report, he had completed spraying a field and was returning to the airport while cruising at 175 mph between 6,500 and 6,800 feet msl. He reported that "the engine popped and white smoke came out of the exhaust" followed by a loss of engine power. During the forced landing attempt on a road, the airplane struck a barbed wire fence, and the left main landing gear hit a "bull hole" and sheared off. Damage included a torn right flap, crushed left elevator leading edge, and a torn-off spreader.
Fuel Information
The pilot stated that he departed with 250 gallons of fuel and flew for approximately 2 hours and 20 minutes. Normal fuel consumption was about 75 gallons per hour. The fuel gauge indicated 1/4 remaining in the left tank and between 1/4 and 1/2 in the right tank. The aircraft was equipped with a Shadin fuel flow monitoring system, which showed 65 gallons remaining at the accident site. After recovery, the salvage company estimated about 25 gallons of fuel were drained from the wings.
Engine and Fuel System Examination
A preliminary engine examination on April 27, 2010, at George's Aircraft in Vernon, Texas, revealed no anomalies in filters, chip detectors, or borescope. On May 11, 2010, the fuel pump and fuel control unit (FCU) were tested at Pratt & Whitney Canada (P&WC) in Montreal. The fuel pump was within ATP limits. The FCU was slightly high on Wf, but P&WC stated this would not have contributed to the power loss. The FCU base showed a small amount of organic debris in the bellows cavity, considered unremarkable. No defects or damage were found that would have prevented normal operation. The Py line from the governor to the FCU pressure tested satisfactory.
On June 21 and 22, 2010, the engine was examined and disassembled at P&WC facilities in Bridgeport, West Virginia. The engine ran in a test cell without anomalies. Although engine trim was slightly out of specifications, acceleration and deceleration were normal. Disassembly of the combustion chamber revealed no anomalies.
Conclusion
The investigation did not identify a specific cause for the engine power loss.