Air Tractor Inc AT-302 N3650B accident near Winnie, Texas

Probable cause

The improper decision by the pilot to attempt a flight with a known fuel system-related maintenance discrepancy, which resulted in a fuel imbalance and subsequent fuel starvation during an approach to an alternate airport with a rough field. Contributing to the accident were the manufacturer's failure to incorporate a warning on AT-302 airplanes and to add a warning about this issue in the AT-302 flight manual.

NTSB analysis

The pilot stated that, on previous flights, he noticed that the cockpit fuel quantity gauge indicated greater fuel consumption from the left fuel tank than the right fuel tank. However, during the accident flight, the fuel quantity gauge indicated greater fuel consumption from the right fuel tank than the left fuel tank. The airplane was not equipped with a fuel tank selector switch. Due to his concern about the fuel quantity imbalance, the pilot decided to land at an alternate airport. However, the engine experienced a total loss of power while the pilot was banking the airplane for landing, so he chose to land the airplane on a rough field. The airplane's left wing struck the ground, and the left main landing gear broke off. Postaccident examination of the airplane found no usable fuel in the right wing fuel tank and about 22.9 gallons of fuel in the left wing fuel tank. No contamination was found within the fuel supply. The airplane manufacturer issued Service Letters Nos. 178 and 178A in 1999 and reissued them in 2002, 2004, and 2009, to advise operators that a fuel imbalance could occur and lead to fuel starvation. A warning placard was never incorporated on AT-302 airplanes, only on later models, and no warning about this issue was added to the AT-302 flight manual.

Text from the NTSB. Open the NTSB docket for CEN13LA283 for the full record.