Air Tractor Inc AT-602 N5007R accident near Allport, Arkansas

Probable cause

A partial loss of engine power due to fuel contamination from foreign object debris. Contributing to the accident was the operator’s failure to follow the manufacturer’s required airframe fuel filter inspection interval.

NTSB analysis

The aerial application airplane was loaded with chemical for application on a rice field. Immediately after the takeoff from the private airstrip, the pilot heard a “loud pop” noise from the turboprop engine, and he observed flames emit from the left side of the airplane. During the forced landing, the pilot reported that it felt like there was a “slight recovery” of engine power, but then the engine ceased producing power. During the forced landing, the airplane nosed over and came to rest inverted, resulting in substantial damage to the left wing, the fuselage, and the empennage.

Examination of the airframe revealed foreign object debris (FOD) between the airframe fuel filter pleats and in the fuel filter bowl. Examination of the engine revealed contamination of the engine fuel filter and various fuel wetted accessories. The engine exhibited rotational contact signatures on the compressor turbine and the power turbine components consistent with the engine producing power at the time of impact; however, the engine power output at the time of impact could not be determined. Marks on the piston, cylinder, and blade damage indicated the propeller was operating at low blade angles with low or no power at impact. Chemical testing of the FOD samples from the airframe and the engine revealed a composition consistent with an unknown fertilizer-type material.

A review of the airplane’s maintenance records revealed that the airplane was flown about 44 hours past the manufacturer’s required fuel filter inspection interval.

It is likely that contaminated fuel obstructed the engine fuel filter and was injected into the engine, which resulted in a partial loss of engine power. The source of the FOD and how it entered the fuel tanks could not be determined based on the available information. It is possible that, had the operator completed the airframe fuel filter inspection within the required interval, the contamination of the filter may have been identified.

Text from the NTSB. Open the NTSB docket for CEN22LA228 for the full record.