What happened
On July 22, 1966, a Beech Bonanza E-35, registration HB-EIX, was performing a flight from Milan Linate to Locarno. As the pilot was maneuvering into the landing pattern, the engine RPM dropped significantly. In an attempt to restore power, the pilot utilized the manual fuel pump, but the engine power continued to decline. Realizing the aircraft could no longer reach the runway, the pilot performed a forced landing approximately 20 and 200 meters short of the threshold. During the landing roll, the aircraft struck a wire fence, causing substantial damage to the left wing and minor damage to the right wing. All three occupants escaped the incident without injury.
The investigation
Investigators examined the fuel system and the fuel levels in the aircraft's three tanks. Upon inspection, it was noted that the left tank was approximately two-thirds full and the fuselage tank was about half full, but the right tank contained only about 0.1 liters of fuel. The investigation focused on the state of the fuel selector valve and the sequence of the pilot's actions during the approach. A flight instructor who arrived at the scene found the fuel selector valve set to the OFF position. When the valve was moved to the left tank and pressure was restored via the manual pump, the engine restarted immediately.
Findings
The investigation established that the engine failure was caused by a lack of fuel delivery to the carburetor. While the pilot believed he had switched the fuel selector from the right tank to the left tank during a 180-degree turn, evidence suggests he likely moved the valve to the OFF position instead. The time elapsed between the valve movement and the engine failure—approximately 60 to 90 seconds—was consistent with the time required to exhaust the residual fuel remaining in the fuel lines and carburetor. The pilot's attention was likely divided by landing preparations and monitoring the airfield traffic, leading to the error.