What happened
On July 21, 2007, at approximately 11:40 local time, a homebuilt Storm 400, registration I-KITS, was participating in the "58th Giro aereo di Sicilia" aerial demonstration. The flight was a scheduled regularity check involving a route from Palermo Boccadifalco, passing over Cefalù, Canicattì, and Bagheria, before returning to the departure point.
After nearly two hours of flight, while approaching Bagheria at approximately 3,500 feet and roughly 3 nautical miles from the coast, the pilot experienced abnormal engine behavior followed by a complete engine shutdown. The pilot attempted several emergency procedures, including activating the fuel pump, checking tank selectors, and testing the magnetos, but was unable to restore engine power.
Faced with the loss of power, the pilot initially prepared for a water landing in the sea but instead identified a deserted stretch of beach at Aspra Beach. The aircraft touched down on the shoreline at approximately 12:05. While the initial contact was stable, the landing gear collapsed during the deceleration phase, causing the aircraft to skid on its nose for several meters. The pilot and passenger both exited the aircraft without injuries.
The investigation
The ANSV examined the aircraft's fuel system and the circumstances surrounding the engine failure. The investigation noted that the aircraft was equipped with two aluminum wing tanks feeding a central collection sump. The fuel system utilized a configuration where fuel could flow between the two tanks, but the connection to the sump was restricted by the placement of the outlet holes.
Investigators found that while the aircraft had departed with 5 and 50 liters of fuel—sufficient for the mission—the fuel distribution was uneven upon inspection. The left tank contained approximately 20 liters, while the right tank was completely empty. The investigation also noted that the fuel filler cap area was designed in a way that could collect debris, which might potentially enter the tanks during refueling. Additionally, the fuel level sensors were noted to be unreliable during changes in aircraft attitude.
Findings
- The engine failure was caused by fuel starvation.
- The fuel system design allowed for fuel to transfer between tanks, but the specific placement of the outlet holes prevented all fuel from being drained from the tanks during certain aircraft attitudes.
- The configuration of the T-junction connecting the tanks to the collector could allow for the formation of air bubbles during turns, potentially interrupting fuel flow.
- The narrow diameter of the fuel lines made the system susceptible to blockages from small impurities or debris.
- It is hypothesized that fuel may have transferred from the right tank to the left tank due to the aircraft's pitch, or that a momentary blockage or air bubble caused the engine to stop.