What happened
On March 1, 2007, at approximately 16:42 UTC, a Hughes 269C helicopter departed from Stockerau airfield for a training flight involving circuit patterns. The crew, consisting of a flight instructor and a student pilot, was performing several circuits when the instructor suddenly detected unusual noises and vibrations within the aircraft. At an altitude of approximately 1,500 to 1,700 feet AMSL, the instructor took control of the aircraft and initiated an autorotation procedure.
The instructor attempted to land the helicopter in a field near the Leitzersdorf wind turbines. During the final approach and transition to landing, the helicopter tilted to the right across its longitudinal axis. The aircraft struck the ground, causing the main rotor blades to make heavy contact with the terrain. The helicopter sustained substantial damage, but both occupants were able to evacuate the aircraft independently and sustained no injuries.
The investigation
The Austrian Federal Safety Investigation Board (SUB) conducted an investigation into the accident, examining the aircraft, the crew, and the flight conditions. Investigators reconstructed the flight path using eyewitness accounts, statements from the crew, and data retrieved from a mobile GPS device, as no flight recorder was installed in the aircraft.
A technical examination of the engine, the main rotor control, and the tail rotor control was performed. This investigation focused on determining whether a mechanical failure had prompted the pilot's emergency maneuvers. Additionally, the investigation reviewed the pilot's qualifications, the aircraft's maintenance status, and the meteorological conditions at the time of the occurrence.
Findings
- The investigation established that the aircraft was fully airworthy and all required documentation and maintenance were in order.
- No mechanical failures or technical malfunctions were found in the engine, the main rotor, or the tail rotor systems; no technical cause for the perceived vibrations was identified.
- Meteorological conditions were favorable and played no role in the accident.
- The pilot's decision to initiate an autorotation rather than attempting a controlled emergency landing was a critical factor.
- The primary cause of the accident was controlled flight into terrain (CFIT), driven by a failed landing during the autorotation procedure and a lack of situational awareness by the pilot during the maneuver.