What happened
On 18 November 2003, a Gazelle HT Mk 2, registration G-CBFD, was involved in an accident near Doncaster, South Yorkshire, during a private flight. Earlier that day, the pilot had experienced a failure in the aircraft's compass system. After consulting with a maintenance engineer via telephone, the pilot attempted to perform a diagnostic procedure to verify the compass functionality.
Following the engineer's guidance, the pilot started the engine and transitioned the aircraft into a hover to perform a 360-degree turn. During the initial checks, the pilot had unbuckled the five-point harness because the connected strap was causing discomfort while sitting in the pilot's seat.
As the helicopter turned into the wind, the pilot found it impossible to maintain level flight. The aircraft began to descend and drift downwind. Upon inspection, the pilot discovered that the unfastened harness buckle had become lodged between the seat and the friction nut at the base of the cyclic control, severely restricting control inputs. In an attempt to recover, the pilot used the yaw pedals to turn the nose back into the wind, but the tail of the aircraft struck the ground during the maneuver. The aircraft was damaged beyond economic repair, though the pilot escaped without injury.
The investigation
way The AAIB examined the cockpit configuration and the mechanics of the control interference. The investigation established that the harness buckle, which is attached to the front of the seat, had moved into a position where it obstructed the primary flight controls. The investigation also reviewed the pilot's actions during the telephone-guided troubleshooting process.