What happened
On 15 August 2009, a Ryan ST3KR, registration N 560028, was performing a private flight from Seppe Airport in the Netherlands to Diest Airfield (EBDT) as part of a four-aircraft formation. While on final approach to runway 24, the engine began to sputter and eventually lost all power.
In an attempt to maintain airspeed and reach the grass area beyond the airfield perimeter, the pilot lowered the nose. The aircraft touched down on the shoulder behind a ditch along the airfield boundary. The impact with the shoulder and subsequent contact with a fence and concrete poles caused the aircraft to rotate forward. The fuselage ended up upside down, resulting in substantial damage to the aircraft. The two occupants sustained minor injuries.
The investigation
The investigation focused on the engine's loss of power and the aircraft's fuel management. Investigators examined the fuel system and found that the fuel tank was nearly empty at the time of the engine shutdown.
Key elements examined included:
- The position of the fuel tank selector, which was found set to "Reserve."
- The reliability of the fuel gauge, which was found to be inaccurate and indicated approximately 3 gallons remained even when the tank was empty.
- The pilot's pre-flight procedures, specifically the reliance on the fuel gauge rather than a physical dipstick measurement.
- The flight's fuel consumption, noting that the flight was conducted at a lower speed to match the formation, which can increase specific fuel consumption.
Findings
- The primary cause of the accident was engine shutdown due to fuel starvation.
- The pilot failed to accurately determine the actual fuel quantity remaining before takeoff, relying instead on an unreliable gauge.
- The crew had established a practice of flying exclusively on the "Reserve" setting to avoid the delay in fuel delivery associated with switching from "Main" to "Reserve."
- The Pilot Operating Instructions provided insufficient detail regarding the specific fuel capacity available when the selector is in the "Reserve" position.
- The fuel gauge was non-functional for precise measurement, as it provided a false reading of remaining fuel.