N622AW

On July 17, 2024, about 1500 central daylight time, an Air Tractor AT-602 airplane, N622AW, was substantially damaged when it was involved in an accident near Oakland, Nebraska. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 137 agricultural flight.

The pilot reported there was a loss of engine power while the airplane was in an aerial-application spray turn. The airplane’s aft fuselage was substantially damaged during the subsequent forced landing in a cornfield.

A postaccident review of the airplane’s digital engine monitor revealed that there was about 180 gallons of fuel distributed between the left-and-right wing fuel tanks before the flight departed, but there was a fuel load imbalance with about 105 gallons in the left-wing fuel tank and 75 gallons in the right-wing fuel tank. After departure, but before the pilot commenced flying aerial-application spray passes, the fuel imbalance had decreased to about 10 gallons between the wing fuel tanks. However, as the pilot conducted spray passes there was a net decrease of fuel from the right-wing fuel tank, with a minimal decrease of fuel from the left-wing fuel tank. Ultimately, about 1 hour 4 minutes into the flight, the right-wing fuel tank quantity decreased to zero gallons, and about 6 minutes later there was a sudden loss of fuel flow and corresponding loss of engine power.

Further review of the engine monitor data revealed a history of fuel imbalance during the previous 3 flights during which the fuel quantity in each tank would fluctuate at least ± 10 gallons during each spray pass. However, unlike the accident flight, after an initial decrease in fuel quantity from either the right-or-left fuel tank there was a measured increase in fuel quantity to that same fuel tank. This observed increase in fuel quantity in a tank was observed in both the left-and-right wing fuel tanks during separate portions of the previous 3 flights. Specifically, when one wing fuel tank showed a decrease in fuel quantity the opposite wing fuel tank either yielded a minimal decrease or a net increase in fuel quantity as the flight progressed. This nonuniform depletion of fuel from each fuel tank was primarily observed while the pilot conducted aerial-application spray passes. There were other portions of the flight, presumably as the pilot flew to/from a field, where any fuel imbalance trended toward a more-balanced fuel load.

The Air Tractor AT-602 fuel system consists of two 108-gallon wing fuel tanks that are interconnected by a 2-gallon header tank. The airplane is not equipped with a fuel tank selector, only a fuel system shutoff valve that is downstream of the header tank.

The airplane wreckage was retained for further examination.