What happened
While performing wildlife control activities, the helicopter suffered a catastrophic engine failure at an altitude of 40 feet above ground level. In an attempt to recover lost power, the pilot tried to regain engine performance by "milking the collective." Despite these efforts, the aircraft impacted the ground in a level attitude without any flare. Following the initial contact with the ground, the helicopter bounced 13 feet forward and rolled to the right.
The investigation
An examination of the engine identified that the connecting rod cap bolts for the #3 cylinder had fractured. This failure led to the catastrophic destruction of the piston and the bearing cap. A metallurgical analysis conducted by the safety board determined that the fracture features located at the center of each bolt were caused by overstress separations. However, investigators noted that mechanical damage near the outside diameter of each bolt had destroyed the original fracture features, making further analysis of those specific areas impossible.