N9197FAir Tractor AT-802A · 1994

The pilot reported that, while maneuvering over a field for the aerial application flight, the airplane’s wing struck a windmill that he did not see. The airplane subsequently collided with terrain and a postimpact fire ensued, which destroyed the airplane. The pilot reported that there were no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation.

On April 21, 2010, approximately 1815 central daylight time, an Air Tractor AT-802A, N9197F, registered to and operated by Aero Tech, Inc., Clovis, New Mexico, was substantially damaged when its engine lost power and the pilot was forced to make an off-airport landing in a field 20 miles south of Alpine, Texas. Visual meteorological conditions prevailed at the time of the accident. The aerial application flight was being conducted under the provisions of Title 14 Code of Federal Regulations (CFR) Part 137 without a flight plan. The pilot was not injured. The local flight originated from Alpine-Casparis Municipal Airport (E38), Alpine, Texas, approximately 1610.

According to the pilot's accident report, he had finished spraying a field and was returning to the airport. The airplane was cruising at 175 mph between 6500 and 6800 feet msl when the "the engine popped and white smoke came out of the exhaust" and the engine lost power. The pilot attempted to land on a road but the airplane struck a barbed wire fence and the left main gear hit a "bull hole" and sheared off. The right flap was torn loose, the left elevator leading edge was crushed, and the spreader was torn off.

The pilot told FAA inspectors that he took off with 250 gallons of fuel. He flew for about 2 hours and 20 minutes. He said normal fuel consumption is about 75 gph (gallons per hour). The pilot further stated that the fuel gauge registered 1/4 fuel remaining in the left tank and ¼ to 1/2 fuel remaining in the right tank. The airplane was equipped with a Shadin fuel flow monitoring system that measures fuel flow to the engine and calculates gallons remaining. The pilot said he resets the system when the airplane is refueled. The Shadin fuel flow monitoring system was showing 65 gallons remaining at the accident site. When the airplane was retrieved, the salvage company estimated about 25 gallons of fuel was drained from the wings.

A preliminary engine examination was conducted at George's aircraft in Vernon, Texas, on April 27, 2010. The filters, chip detectors, and borescope of the engine revealed no anomalies.

On May 11, 2010, the fuel pump and fuel control unit (FCU) were tested at facilities of Pratt &Whitney Canada (P&WC) in Montreal. The fuel pump was within ATP limits. The fuel control unit (FCU) was slightly high on Wf but, according to P&WC, this would not have contributed to the power loss. The FCU base was removed to inspect the drive-bearing. There was a little organic debris in the bellows cavity, but this was not considered unusual. No defects or damage to the fuel pump or FCU was found that would have precluded normal operation. The Py line from the governor to the FCU pressure tested satisfactory.

The engine was examined and disassembled at the facilities of P&WC in Bridgeport, West Virginia, on June 21 and 22, 2010. The engine ran in a test cell with no anomalies. Engine trim was slightly out of specifications, but acceleration and deceleration were normal. Disassembly of the combustion chamber revealed no anomalies.