What happened
On August 8, 1998, a Westland-Bell 47 G-3 helicopter was conducting a private sightseeing flight with two passengers near the Finow airfield. The pilot, who was also the owner and operator of the aircraft, initiated a takeoff from the airfield's taxiway into the wind at a low altitude.
As the aircraft accelerated to speeds between 40 and 60 km/h and began its climb, it passed over a hangar located directly on the departure path. During this climb, the helicopter began to rotate uncontrollably around its vertical axis to the right. After completing several rotations, the aircraft struck the ground. Although all occupants managed to evacuate the aircraft safely, the helicopter subsequently caught fire and was destroyed. There were no injuries resulting from the accident.
The investigation
The BFU investigation focused on determining whether mechanical failure contributed to the loss of control. Investigators examined the scene and performed a technical analysis of components from the tail rotor drive and the control systems, which were transported to Braunschweig for examination. Based on statements from the pilot and the passengers, who were considered knowledgeable observers, investigators found no evidence of technical malfunctions. All damage to the aircraft was determined to be a direct result of the impact.
Findings
- The primary cause of the accident was a pilot error involving insufficient monitoring of the rotor RPM during the climb.
- The pilot failed to notice or reacted too late to a drop in rotor speed.
- This drop in RPM led to a reduction in tail rotor effectiveness, causing the helicopter to spin around its vertical axis.
- Due to the low altitude of the aircraft while passing over the hangar, the pilot had insufficient time to recover from the resulting emergency.