What happened
On March 13, 2017, at approximately 13:20 UTC, an EMB-202 aircraft, registration PT-AXY, was performing agricultural spraying operations near the Alegrete Aerodrome in Rio Grande do Sul, Brazil. The aircraft was engaged in a local flight to spray a soybean crop.
While performing a reversal turn to begin the final application pass, the pilot attempted to switch fuel tanks using the fuel selector valve. During this maneuver, the engine began to fluctuate and subsequently lost power. Because the aircraft was flying at an extremely low altitude—approximately two meters above the ground—the pilot was unable to recover the engine despite multiple attempts to reposition the selector. The pilot performed an emergency three-point landing in a grassy area, where the aircraft struck termite mounds. The impact caused substantial damage to the engine, propeller, landing gear, and left wing.
The investigation
CENIPA investigators examined the fuel system and the pilot's actions during the maneuver. The investigation confirmed that the fuel selector valve was functioning correctly in all positions and that sufficient fuel was available in both tanks to continue the flight.
Investigators determined that the pilot, while attempting to switch from the left tank to the right tank, inadvertently rotated the selector valve in a counter-clockwise direction. Since the valve was already set to the left tank, this movement placed the valve in the "Closed" (F) position, effectively cutting off the fuel supply to the engine. The investigation also noted that the pilot's attention was focused outside the cockpit for the application task, making the selector difficult to monitor. Additionally, the pilot performed the fuel switch during a low-altitude turn, a phase of flight where error correction is nearly impossible.
Findings
- The engine failure was caused by the inadvertent closing of the fuel selector valve.
- The pilot attempted to switch fuel tanks during a low-altitude reversal turn, which is an unstable flight condition.
- The physical location of the selector valve required the pilot to look down, which was difficult while maintaining external visual scanning during spraying.
- The pilot's attention and piloting judgment were contributing factors to the occurrence.
Safety action
CENIPA recommended that the National Civil Aviation Agency (ANAC) disseminate the lessons learned from this investigation to alert agricultural pilots and operators to the risks of switching fuel tanks outside of stable flight conditions (straight and level flight at a safe altitude).