What happened
On August 17, 2017, at approximately 07:35 UTC, a Schweizer 269C helicopter departed from Wels Airport (LOLW) for an aerial photography mission. The flight, which included a pilot and a photographer, was conducting low-level circular patterns at an average altitude of 250 meters AGL over several locations in Upper Austria.
Approximately one hour into the flight, while operating near Stadl, the crew noticed unusual engine noises followed by a significant loss of engine power. The pilot immediately initiated an autorotative descent from an altitude of approximately 250 meters AGL at a speed of 60 knots. While attempting to target a field near Neuhofen, the pilot identified a pile of grass clippings obstructing the intended landing site. To avoid this obstacle, the pilot opted for a sliding landing on an adjacent field.
The helicopter struck the ground approximately 30 meters west of the obstruction at a heading of 110 degrees. The aircraft slid for about 40 meters before coming to rest on its right side. The pilot was able to exit the aircraft uninjured, but the photographer became trapped, with her head and right shoulder wedged against the cabin frame. First responders arrived at the scene to assist with the extraction.
The investigation
The Austrian Federal Safety Investigation Board (SUB) examined the aircraft' and engine components following the accident. The investigation focused on the mechanical state of the Lycoming HIO-360 engine, specifically looking for evidence of ignition system failure or spark plug fouling. Technical inspections of the engine were conducted, including an examination of the spark plugs and the cylinder threads.
Investigators also reviewed maintenance records and interviewed witnesses to reconstruct the sequence of events leading to the power loss. The investigation included a review of the engine's maintenance history, specifically regarding the 50-hour inspection interval and the procedures for checking the ignition system.