What happened
On 11 September 2000, a Bell 206B, registration G-LGRM, departed Caernarvon to perform a pipeline survey across North Wales. While the initial weather forecast indicated manageable conditions, the aircraft encountered rain showers and reduced visibility as it approached the Snowdonia region. The cloud base was observed to be between 1,000 and 1,500 feet.
To maintain visual contact with the ground amidst deteriorating conditions, the pilot executed a turn to the left toward a steep hillside while simultaneously descending. During this maneuver, an unidentified amber caution light illuminated on the central warning panel. Simultaneously, the aircraft experienced an uncommanded yaw to the right. The pilot attempted to use the pedals to correct the motion but was unable to stop the rotation. In an effort to regain control, the pilot turned into the direction of the yaw, which caused the aircraft to intermittently enter cloud cover. The helicopter eventually struck the ground and was destroyed. Both the pilot and the passenger sustained minor injuries.
The investigation
The AAIB investigated the accident using the pilot's report and subsequent inquiries. Investigators examined the wreckage to determine the cause of the uncommanded yaw. The examination of the tail rotor drive system revealed that it was fully functional at the time of impact. Additionally, the investigation could not confirm the specific nature of the amber caution light seen by the pilot, as the pilot was unable to identify which specific warning had illuminated.