What happened
On June 18, 2024, at approximately 13:18 local time, an Airbus Helicopters AS 350 B3, registration HB-ZLK, was engaged in a logging operation in the Chalttobel area, within the municipality of Conters im Prättigau, Switzerland. The aircraft, operated by Swiss Helicopter AG, was performing work under Visual Flight Rules (VFR) when it attempted to place a heavy log on the ground. During this process, immediately after the transported log made contact with the earth, the helicopter began to rotate around its vertical axis. This uncontrolled spinning continued until the aircraft struck the ground with significant force.
The investigation
The Swiss Transportation Safety Investigation Board (SUST) launched an inquiry into the incident to determine the sequence of events leading to the impact. The investigation focused on the mechanics of the load release and the subsequent aerodynamic behavior of the aircraft during the logging maneuver. The investigation confirmed that the aircraft sustained heavy damage and that fuel was spilled during the impact. The pilot sustained serious injuries during the crash.
Findings
- The primary cause of the accident was the uncontrolled rotation of the aircraft around its high axis following the contact of the payload with the ground.
- The incident occurred specifically during the phase of the flight involving the placement of a log.
- The impact resulted in significant structural damage to the Airbus Helicopters AS 350 B3.