Background
The pilot was asked by the operator to fly the helicopter prior to the operator signing a leaseback agreement with the reported owner.
First Incident
During an initial air taxi to a helipad, the helicopter began to oscillate in a ground resonance event, causing the attempt to be aborted. Before this attempt, the oleo struts appeared equally extended. After the event, the struts were low, and one was flat.
Second Incident
Approximately 18 days later, after the pilot was told that the struts had been taken care of and that the owner had been flying the helicopter, a planned air taxi to a helipad was attempted. The helicopter again experienced a ground resonance event with severe oscillations to the point of destruction. The pilot reported that he lowered the collective and decreased the throttle when the oscillations began.
Aftermath
Attempts to obtain the maintenance records and components of the helicopter for testing were unsuccessful.