What happened
On October 27, 2017, a Piper PA-28-181, registration HB-PKR, was conducting a training flight under Visual Flight Rules (VFR) near Bercher, Switzerland. The flight, operated by AeroFormation B.Hanhart SA, originated from La Blécherette airfield. During the flight, the crew initiated a simulated engine failure procedure over clear terrain to practice emergency landing techniques.
As part of the drill, the pilot performed the necessary troubleshooting steps and adjusted the fuel tank selector. However, during the go-around attempt at a low altitude, the engine ceased operation. The instructor in command subsequently performed an emergency landing at a location known as "Le Bochet." While there were no fatalities, one occupant sustained slight injuries.
The investigation
The investigation focused on why the engine failed during a procedure intended to be a simulation of a failure rather than an actual loss of power. Upon inspecting the aircraft on the ground, the crew identified that the fuel selector valve had been moved to the "OFF" position instead of the intended "RIGHT" tank position. The investigators examined the mechanical state of the fuel system to determine how this selection occurred during the maneuver.
Findings
The primary cause of the engine shutdown was that the fuel selector was set to the OFF position during the flight. The investigation established that a defective safety mechanism on the selector valve allowed it to be moved to the closed position, which directly led to the loss of fuel flow and the subsequent engine failure during the low-altitude go-around.