CH146420 Griffon
18 July 2002
Goose Bay, Labrador
The crew was conducting a Search and Rescue (SAR) mission about 100 nautical miles from Goose Bay when Rescue Coordination Centre Halifax cancelled the mission because the target had been located. The weather was marginal visual flight rules. The crew started the return leg to 5 Wing, when, in normal cruise flight at 200-300 feet above ground level, the tail rotor departed the aircraft. About 400 meters down track, the aircraft crashed into hilly, tree-covered terrain. Both pilots were killed instantly and both the SAR Technician and Flight Engineer were seriously injured. Despite his injuries, the Flight Engineer was able to render first aid to his crewmates. He used a satellite phone to report the accident to RCC Halifax. A 444 Squadron rescue helicopter arrived on scene to evacuate the survivors to medical facilities within 3 hours. The aircraft was destroyed.
The investigation revealed that while in cruise flight, the tail rotor of CH146420 failed due to a fatigue crack initiating from a small damage site on the skin of the rotor blade about 18.5 inches from the tip of one blade. That section of one blade then flew off; the resulting imbalance of this dynamic component caused the tail rotor input shaft to fail instantly and the entire tail rotor to depart the aircraft. The change to the aircraft's centre of gravity with loss of mass of the tail rotor created a nearly instantaneous and extreme out of normal flight condition which was compounded by the low altitude, terrain, and weather conditions.
Contributing factors included tail rotor inspection (frequency and criteria), and aircrew autorotation training.
A total of 39 safety recommendations resulted from this accident. These recommendations are aimed at DND, Transport Canada, the United States Federal Aviation Administration, and Bell Helicopter.
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