Accident Details
On June 13, 2014, at approximately 1100 Pacific daylight time, an Air Tractor AT-502B, registration N502JS, was substantially damaged during takeoff from a dirt airstrip near Princeton, California. The accident followed a reported partial loss of engine power. The airplane was operated by Michaud Aviation of Willows, California, under Title 14 Code of Federal Regulations Part 137 for agricultural operations. The commercial pilot, the sole occupant, was not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local aerial application flight, which was originating at the time.
Aircraft and Pilot Information
The aircraft was an Air Tractor AT-502B, a single-engine agricultural airplane. It was registered to a private individual. The pilot held a commercial certificate and was the sole occupant.
Sequence of Events
According to a written statement from the pilot to the National Transportation Safety Board (NTSB) investigator-in-charge, the airplane was loaded with approximately 3,000 pounds of fertilizer in the hopper and about 115 gallons of Jet A fuel. During takeoff to the north from the dirt airstrip, the airplane lifted off about two-thirds down the runway. As it reached an altitude of about 10 to 15 feet above ground level, the pilot sensed a partial loss of engine power, and the airplane began to settle. The pilot applied full power, but the engine still seemed to produce only partial power. Subsequently, the airplane impacted the ground and came to rest upright.
Post-Accident Examination
Local law enforcement examined the airplane and found that the fuselage was displaced to the right forward of the vertical stabilizer, and the right aileron was partially separated. The aircraft was recovered for further examination.
The NTSB investigator examined the airframe and engine on July 31, 2014, at Air Transport in Phoenix, Arizona. The engine remained attached via all mounts, and all fuel, oil, and pneumatic lines were secure. Continuity was established from cockpit controls to the engine. The engine was removed and sent to the manufacturer for examination. The airframe was mostly intact. The fuel selector valve was found in the "OFF" position. When placed in the "ON" position, compressed air applied to the right fuel inlet port (with the left port blocked) resulted in fuel expelling from the engine supply line. The fuel filter drain plug was removed, and a fuel sample was free of debris. Due to impact damage, airframe electrical power was unavailable, but an external battery connected to the fuel pump wires allowed the pump to actuate normally. The left and right wing fuel vents were clear of debris.
Engine Testing
The PT6A-34AG engine, serial number PCEPH0183, was examined at Pratt & Whitney in Bridgeport, West Virginia, on December 3, 2014. All accessories were intact. The chip plug detector was free of debris. Borescope inspection of turbine blades and vanes showed normal operational signatures. The engine was installed in a test cell using a slave starter and tach drive, and run for about 40 minutes at various power settings with no anomalies noted.