What happened
On April 26, 2014, a Piper PA-18 «150» Super Cub, registration HB-PIJ, was performing a takeoff from the grass runway 26C at Locarno Aerodrome (LSZL) under visual flight rules. Shortly after takeoff, while climbing at an altitude between 50 and 80 meters, the engine suddenly lost power. Although the propeller continued to rotate, the pilot was unable to maintain flight.
In an attempt to reach runway 08R, the pilot initiated a left-hand turn. During this maneuver, the aircraft entered a stall and struck a grassy field near the threshold of runway 08R with a steep bank and nose-down attitude. The impact resulted in two serious injuries for the occupants, the pilot and a passenger. There was no post-crash fire, and emergency services arrived at the scene relatively quickly.
The investigation
The Swiss Transportation Safety Investigation Board (SISI) examined the wreckage and the engine components. Investigators found that the fuel selector valve was in the "CLOSED" position. While the engine showed various signs of wear and corrosion, none of the technical anomalies could definitively explain the sudden loss of power. However, the investigation focused on the fuel delivery system and the pilot's decision-making.
Technical analysis of the fuel selector revealed that the control lever had excessive play, and the red triangular indicator was loose, which could lead to confusion regarding the actual setting. Furthermore, investigators noted that the passenger's shoulder harness failed during the impact due to wear, contributing to the severity of the injuries.
Findings
- The primary cause of the accident was a loss of control during a low-altitude turn following an engine power loss.
- The engine power loss was likely caused by a fuel starvation issue, potentially due to the fuel selector being incorrectly positioned.
- The pilot's decision to execute a 180-degree turn at a very low altitude was inappropriate, as the aircraft's stall speed increases during such maneuvers.
- An emergency landing could have been successfully performed by making a trajectory change of less than 45 degrees toward the right side of the takeoff runway axis.
- The fuel selector mechanism was prone to error due to excessive play in the lever and the indicator plate.