What happened
On March 10, 2009, at approximately 12:19 UTC, a helicopter of the type AS 350 B1 departed from Graz Airport (LOWG) for a search mission to locate a missing person. The crew, consisting of a pilot and a flight operator, picked up a police officer at a sports field in Frauental around 12:30 UTC to assist with the search.
After conducting a brief search in a forested area near Frauenegg, the pilot attempted to fly toward the western side of Deutschlandsberg to continue the mission. During a steep right turn over a densely populated area, the flight operator noticed an unusual vibration, a metallic noise, and a loud audible warning signal. The helicopter subsequently lost significant altitude. During the descent, the tail rotor strike and skid made initial contact with the chimney casing of a two-story house near the riverbank. The aircraft then struck a nearby meadow at a steep angle, resulting in the total destruction of the airframe.
The investigation
The Austrian Federal Safety Investigation Board (SUB) reconstructed the flight path using eyewitness accounts, GPS data from a Garmin 296 device, and radar data. The investigation focused on the mechanical state of the engine and the fuel system. Investigators examined the wreckage, including the engine components, the fuel control unit (FCU), and the fuel/oil heat exchanger. Technical analysis involved inspecting the fuel pump, the fuel filter, and the internal components of the fuel control unit to identify any signs of blockage or mechanical failure.
Findings
- The investigation established that the engine experienced a sudden loss of power during the maneuver.
- A failure within the fuel control unit (FCU) was identified as the primary cause of the engine's inability to maintain power.
- The pilot and the passenger (the police officer) both sustained fatal injuries, with the latter passing away six days later in the hospital. The flight operator survived the crash but sustained serious injuries.
- The aircraft was fully fueled with 400 liters of Jet A1 fuel at the time of the accident.