What happened
On May 31, 1998, a Hughes 269 B helicopter was conducting a private sightseeing flight near Plettenberg, Germany. The flight departed at 13:56 from a hangar located at a local company's premises. On board were the pilot in command and the aircraft owner, who was acting as co-pilot for the duration of the flight.
An eyewitness observed the helicopter performing several turns and course changes in the vicinity of the flight path. While the witness did not see the impact, they heard the crash as the aircraft entered a dense forest approximately 4 km east of Plet-temberg. The two occupants were located by emergency services approximately one hour after the accident, both sustaining two serious injuries.
The investigation
The BFU investigation examined both technical and operational aspects of the accident. Technical inspections of the tail rotor drive, tail rotor controls, clutch, freeboard, and the main rotor's collective and cyclic controls showed no evidence of mechanical failure. The engine was also found to have been functioning correctly.
Operational analysis involved reviewing GPS data and witness statements. While the GPS confirmed the maneuvers observed by the witness, it did not support the witness's claim that the helicopter had been flying in circles immediately prior to the crash. The investigation also addressed conflicting statements regarding which individual was acting as the pilot in command, eventually confirming that the pilot with only 80 flight hours was the one controlling the aircraft during the critical maneuvers.
Findings
- The aircraft was in good mechanical condition with no technical defects found.
- The pilot in command, who was relatively inexperienced with only 80 total helicopter flight hours, performed tight turns at low airspeed.
- These maneuvers overwhelmed the performance capabilities of the Hughes 269 B.
- A loss of rotor RPM occurred during these maneuvers, leading to an uncontrollable yaw (rotation around the vertical axis).
- Although the more experienced co-pilot attempted to stabilize the aircraft by initiating an autorotation, the low altitude made it impossible to avoid the forest impact.