Incident Overview
During a maintenance test flight, a helicopter experienced ground resonance. The incident began when a Certified Flight Instructor (CFI) noticed an unusual vibration while conducting student training. The training was suspended, and maintenance personnel were informed.
Attempt to Duplicate Vibration
The pilot subsequently attempted to recreate the vibration for a maintenance mechanic. After two unsuccessful tries, the pilot landed the helicopter on a slight slope. As one skid touched down, the helicopter began to vibrate. The pilot reduced the throttle, which caused the vibration to intensify.
Disintegration
According to the pilot, the helicopter then began to disintegrate. No further details about the extent of damage or injuries are available from the source.