Accident Details
On September 21, 2012, about 1700 Pacific daylight time, an Air Tractor AT-502, registration N4556S, was substantially damaged when it struck transmission wires and impacted terrain during the initial climb after takeoff near Firebaugh, California. The airline transport pilot was not injured. The airplane was operated by Thiel Air Care, Inc., under 14 Code of Federal Regulations Part 137. Visual meteorological conditions prevailed for the aerial application flight, which was originating at the time of the accident. No flight plan had been filed.
Pilot Report
The pilot reported that he ferried the airplane about 25 nautical miles to a private ag-operating airstrip at an elevation of 236 feet. After landing, he went to the office to receive mission details while the airplane was being fully fueled and loaded with 400 gallons of defoliant. During the takeoff roll, the pilot noticed that the engine was not producing its fully rated torque. About halfway down the runway, because the airplane's tail was not rising, he added more flaps to help raise it. At the end of the runway, the airplane struggled into ground effect and would not climb. As the airplane approached a power transmission line about 0.5 miles from the airstrip, the pilot began dumping the defoliant load in an attempt to climb over the wires. Dumping the load resulted in a gain of altitude, but simultaneously the nose came up, leading to a very high pitch attitude. The airplane then struck the wires and landed hard in an open field several hundred feet beyond the transmission line. The impact bent both wings and damaged the landing gear and engine compartment.
Post-Accident Examination
On October 25, 2012, a field representative for the engine manufacturer examined the engine and airplane. No evidence of any preimpact mechanical malfunctions or failures was found. The fuel control unit, fuel pump, fuel heater, and propeller governor were sent to the manufacturer's facility in Quebec, Canada, for further examination. On November 21, 2012, these components were examined and tested under the supervision of an investigator from the Transportation Safety Board of Canada. The testing found no indications of any preimpact mechanical anomalies or dysfunctions that would have precluded normal engine operation.
Weather Conditions
At 1653, the reported weather conditions at Madera, California (elevation 255 feet, about 28 nautical miles east of the accident site) were: wind from 290 degrees at 7 knots; sky clear; visibility 10 miles; temperature 32 degrees Celsius; dew point 7 degrees Celsius; altimeter 29.85 inches of mercury. The calculated density altitude was 2,400 feet.