What happened
On October 5, 1996, a Kit Fox 4-1050, registration HB-YGP, was performing a takeoff from Agno/Lugano Airport. Shortly after departing, the aircraft experienced a sudden loss of engine power. In an attempt to return to the runway, the pilot initiated a left-hand turn at a very low altitude. During this maneuver, the aircraft's airspeed dropped below the minimum safe threshold, leading to a loss of control. The aircraft crashed approximately 100 meters south of the airfield, resulting in one fatality (the pilot) and one serious injury (the passenger). The impact destroyed the aircraft and caused damage to nearby fencing and crops.
The investigation
Investigators examined the aircraft's maintenance history and technical configuration. While the aircraft was operating under a provisional certificate of airworthiness for test flights, it was found that the pilot was not authorized to conduct RSA test flights. The investigation also revealed that an auxiliary electric fuel pump had been installed without the approval of the relevant aviation authorities (RSA or UFAC). Furthermore, this pump was installed in series rather than in parallel, contradicting the manufacturer's instructions.
Regarding the flight dynamics, the investigation noted that the pilot was flying at an extremely low altitude—estimated between 50 and 100 meters—at the time of the engine failure. While the remaining runway length might have been sufficient for an emergency landing if the full length had been utilized, the decision to execute a turn at such low altitude caused the airspeed to decay rapidly, making recovery impossible.
Findings
- The primary cause of the accident was the loss of control during a turn following an engine power loss.
- The specific cause of the engine failure could not be definitively determined, though the improper installation of the auxiliary fuel pump was identified as a highly probable contributing factor.
- The aircraft was not equipped with an Emergency Locator Transmitter (ELT).
- The pilot attempted a banking maneuver at an altitude that provided insufficient margin to maintain minimum flying speed after the power loss.