NTSB Factual Report

On April 17, 2003, approximately 1210 central daylight time, an Air Tractor AT-402B agricultural single-engine airplane, N6078W, was substantially damaged during a forced landing following a partial loss of engine power during the takeoff/initial climb from an airstrip near Taft, Texas. The commercial pilot, sole occupant of the airplane, was not injured. The airplane was owned and operated by Hunt's Ag Air, Inc., of Taft, Texas, under 14 Code of Federal Regulations Part 137. Visual meteorological conditions prevailed, and a flight plan was not filed. The local aerial application flight originated from the operator's private airstrip approximately 3 minutes prior to the accident.

The 3,817-hour pilot reported to the FAA inspector, who responded to the accident site, that approximately 3 minutes after departure he noticed the "power reduced to 70 percent." The pilot turned the airplane into the wind for the forced landing and dumped the chemical load. The airplane landed perpendicular to the furrows in the cultivated field striking the left main landing gear and left wing tip with the ground. Subsequently, the airplane rotated to the left, and the tail section struck the ground.

The FAA inspector reported that both wing tips and both elevators were damaged. The upper and lower longerons, the left main landing gear, and the spray booms were bent.

Visual inspection of the PT6A-34 engine by the FAA inspector revealed that the primary fuel transfer tube was not in its proper position, and the "O" ring was protruding outside of the adapter. Fuel leakage at the fuel transfer tube was confirmed by running the engine and observing the leaking fuel. The engine did not develop power above 72 percent Ng. The fuel transfer tube was secured in its proper position, and the engine developed full power.

Further examination of the engine by the FAA inspector revealed that the fuel transfer tube lock plates at nozzle #4 and #8 were distorted. The secondary transfer tube between the #4 and #5 adapter was found resting on the shoulder of the tube rather than in the groove.

A review of the maintenance records by the FAA inspector revealed that the nozzles had been installed since December 20, 2002, and had accumulated 111 hours time in service. The maintenance entry for the last annual/100 hour inspection on April 8, 2003, stated that an engine compartment cleaning, engine run, and inspection did not reveal any leaks or discrepancies.

According to the manufacturer's representative, operating history of the engine did not reveal evidence of prior fuel leakage resulting from improper placement of the fuel transfer tubes, migration of the fuel transfer tubes out of the fuel adapter, or from bent or distorted lock plates.

NTSB Probable Cause

The partial loss of engine power resulting from a leaking fuel transfer tube following inadequate maintenance by unknown personnel. A contributing factor was the furrowed terrain encountered during the forced landing.