What happened
On June 11, 2002, a Hughes 269C helicopter crashed into a grassy area adjacent to the runway at Paderborn-Lippstadt airport. The flight was part of a series of training maneuvers intended to evaluate the aircraft for a potential charter agreement. The pilot had been performing several circuits, with previous landings completed on the grass strip to the right of the runway.
During the third circuit, the aircraft's flight path changed abruptly. Radio communications indicated that the pilot intended to conclude the circuit with an autorotation. However, during the final approach, the helicopter suddenly veered 30 degrees to the right, heading toward the airfield. Witnesses observed the aircraft descending almost vertically from an altitude of approximately 200 meters, noting a distinct fluttering sound. The helicopter struck the ground with high impact, causing the main rotor blades to strike the tail boom and resulting in the deaths of both occupants.
The investigation
The BFU examined the wreckage, the engine, and the drive system. Investigators analyzed the main and tail rotor components, finding no evidence of pre-existing fatigue or structural failure in the rotor mast or control components. The engine's fuel system and valves were found to be in normal working order, and the spark plugs showed a normal combustion pattern.
Technical reconstruction focused on the drive belt system and the throttle position. Investigators determined that the engine was operating at idle power during the impact. While some blades on the fan disc were broken, the lack of significant grinding marks or extensive engine damage suggested the engine was not under high power at the moment of impact. The investigation also reviewed radar data, which showed the aircraft's flight path and altitude prior to the crash.
Findings
- An unidentified event, either technical or operational, necessitated an immediate landing.
- Inadequate monitoring or management of the engine power and/or main rotor RPM.
- A critical loss of rotor RPM that became aerodynamically unrecoverable.
- An uncontrollable loss of altitude leading to the impact.
- The terrain directly in front of and beneath the helicopter was unsuitable for completing a successful autorotation.
- The significance of the initial triggering event was underestimated by the crew.