What happened
On December 19, 2003, a Vulcanair VF600w prototype, registration I-VAVF, was conducting a flight test program near Naples Capodichino Airport. The flight was part of a type investigation process aimed at future certification. While returning from a testing area near Grazzanise, the pilot noticed an imbalance between the fuel levels in the left and right tanks. To correct this, the pilot had previously turned the right tank selector to the OFF position to consume the excess fuel in the left tank.
During the descent, the pilot attempted to reopen the right tank selector but inadvertently closed the left tank selector as well. This led to a total loss of fuel supply. Shortly after, the "SUMP FUEL LOW" warning light illuminated, and the engine power began to fluctuate before the engine shut down completely at an altitude of approximately 1,200 feet.
With insufficient altitude to reach the runway, the pilot performed an emergency landing in a plowed field in the municipality of Casandoli. The aircraft struck the ground with a steep approach, causing the landing gear to collapse and the wingtips to strike the terrain. The pilot sustained minor injuries, while the aircraft suffered substantial damage to the fuselage, landing gear, and wings.
The investigation
The ANSV investigation focused on the fuel system functionality and the sequence of pilot actions. Investigators examined the aircraft's fuel system, which had been exhibiting an asymmetric drainage issue since the early stages of the flight test program. The investigation also reviewed the telemetry data from the ground station and the configuration of the cockpit controls. The inquiry established that the ground station used by technicians did not display critical warning lights, such as the fuel sump low alarm, which prevented ground personnel from assisting the pilot in identifying the fuel starvation issue.
Findings
- The primary cause of the accident was the engine shutdown due to fuel starvation, triggered by the pilot's unintentional closure of the left fuel tank selector.
- The aircraft's fuel system suffered from a persistent issue with asymmetric drainage between the wing tanks, necessitating frequent manual adjustments to the selectors.
- The cockpit fuel selector panel was inadequately configured, making it difficult to immediately recognize the position of the valves.
- The aircraft lacked the required amber "LH/RH TANK CLOSED" warning lights, which would have alerted the pilot to the selector positions.
- The ground monitoring station lacked the capability to display vital system warning lights, preventing real-time oversight of the aircraft's fuel status by ground technicians.