What happened
On 14 October 2011, a Diamond Katana DA20-C1, registration EC-KDS, was conducting a visual flight training mission near Bilbao, Spain. The crew, consisting of a flight instructor and a student pilot, had completed pre-flight preparations and refueled the aircraft at Bilbao Airport earlier that morning.
At approximately 12:37 local time, the pilot notified air traffic control that the aircraft was experiencing engine failure and that an emergency landing was being attempted at an alternate field. The aircraft was observed gliding toward a harvested field on the outskirts of Amelrio. During the final approach, the aircraft struck the ground violently with its nose and right wing. Both occupants sustained fatal injuries.
The investigation
The CIAIAC investigation focused on the sudden loss of engine power and the circumstances leading to the crash. Investigators examined the aircraft's fuel system, the engine's mechanical condition, and the flight's history.
Post-accident inspections of the wreckage revealed that the fuel tank, engine, and fuel system were completely empty, with no fuel spilled at the crash site. While the engine was found to be mechanically sound through testing on a different aircraft, the investigation identified a significant discrepancy in the fuel levels. Although the aircraft had been fully refueled before departure, the fuel gauge at the time of impact read zero.
Investigators also examined the maintenance drains located on the underside of the fuselage. Although these drains were found in the closed position after the impact, testing demonstrated that if the drain on the fuel return line were left open, fuel could leak at a rate of approximately 1.0 to 1.2 liters per minute while the engine is running, a loss that would be undetectable from the cockpit.
Findings
- The engine stopped due to fuel exhaustion.
- The investigation found that leaving the maintenance drain on the fuel return line open is consistent with the loss of fuel observed during the flight.
- The pilot successfully selected a suitable landing field and executed the glide maneuver correctly, but failed to properly manage the transition to the flare, causing the aircraft to impact the ground with the nose.
- The student pilot, being unfamiliar with this specific aircraft type, may have inadvertently left the maintenance drain open during the pre-flight inspection.
Safety action
- REC 25/13: It is recommended that the manufacturer, Diamond Aircraft Industries Inc., modify the design and location of maintenance drainage systems to ensure they cannot be accidentally manipulated using standard crew drainage tools.
- REC 26/13: It is recommended that the operator, Aerolink, ensure that training for precautionary landings includes the final flare phase and is conducted in diverse settings to prepare pilots for various terrain slopes.