What happened
On July 4, 2017, at approximately 06:21 UTC, an SA 315 B Lama helicopter was performing commercial cargo operations near Dalaas, Austria. The pilot was conducting material transport flights using a 50-meter electric sling load to move branches and wood to a construction site.
After delivering a load of branches, the pilot attempted to land at a nearby refueling point. During the descent, the sling load became entangled with a stack of wood. In an attempt to clear the entanglement, the pilot manipulated the flight controls, moving the cyclic forward and then slightly to the left, before pulling back to prevent forward momentum. During this maneuver, the pilot heard noises indicating that the main rotor blades had made contact with the tail boom.
Following the impact, the tail rotor failed, causing the helicopter to enter an uncontrolled leftward rotation. The pilot attempted an emergency engine shutdown via the fuel shut-off valve in an effort to reach the landing area, but the spinning motion made a controlled landing impossible. The helicopter struck a construction container with its tail boom and subsequently slid down a slope, coming to rest on its side. The pilot was able to exit the aircraft independently and was uninjured.
The investigation
The Austrian Federal Safety Investigation Board (SUB) examined the aircraft, the flight conditions, and the sequence of events. The investigation included interviews with the pilot and witnesses, as well as an analysis of the wreckage and maintenance records. The investigation confirmed that the aircraft's weight and center of gravity were within limits and that the pilot was fully qualified and experienced with the aircraft type. Meteorological conditions were found to be favorable, with no evidence of solar glare or significant weather interference contributing to the accident.