What happened
On July 8, 2005, at approximately 20:12, a pilot departed from the Illertissen airfield for a local flight in a Dallach D4/E-S Fascation. Shortly after takeoff, the engine began to sputter and subsequently failed. Despite attempts to restart the engine, the power loss continued.
While gliding from the northeast, the aircraft crossed a connecting road between Eberslot and Obenhausen at 20:36. The pilot attempted an emergency landing on open terrain, aiming to reach a farm track. During this maneuver, the aircraft's airspeed dropped below the minimum required speed, causing it to bank to the right. The aircraft struck a grain field in a nose-down attitude, resulting in the destruction of the fuselage up to the leading edge of the wings. The pilot sustained serious injuries to the head, hands, and legs and was trapped in the wreckage until rescue teams arrived.
The investigation
The BFU examined the wreckage and the aircraft's systems to determine the cause of the engine failure. Investigators found that the fuel bowls in both carburetors were empty and the forward tank was ruptured and devoid of fuel.
Technical inspection of the engine revealed no mechanical defects. However, the investigation focused on the fuel management system. The aircraft utilized a modified fuel selector valve, originally from a motorcycle, which was operated via an extension linkage protruding through the instrument panel. The investigators also examined the fuel gauge, which utilized a transparent tube to show fuel levels.
Findings
- The engine failure was caused by fuel exhaustion.
- The pilot's assessment of remaining fuel was unreliable because the fuel gauge lacked a zero-liter mark or any calibration scale; the pilot relied on previous experience with a similar aircraft type.
- The fuel selector valve was difficult to operate and showed signs of corrosion in the reserve position area.
- The connection between the fuel valve and the cockpit extension linkage had broken at the point of the modification.
- During the emergency landing, the pilot allowed the airspeed to drop below the minimum required level, leading to the loss of control and the subsequent crash.
- The cockpit lacked proper markings for the fuel selector positions (ON, OFF, RESERVE) on the instrument panel.