What happened
The pilot performed a smooth landing and kept the aircraft on the ground for approximately five to six seconds. After reducing the engine RPM to a range between 2700 and 2800, the pilot noticed vibrations within the helicopter. In an attempt to transition into a hover, the pilot increased the throttle to 3100 RPM. This action resulted in severe vibrations that lasted about one second, at which point the left skid collapsed. The movement caused the main rotor to make contact with the tailboom. Following the incident, the pilot secured and evacuated the aircraft once all motion had ceased.
The investigation
Technical examinations of the landing gear revealed that the charge pressure for all four landing gear dampers was below the levels required by maintenance instructions. The investigation also included an examination of the main rotor head dampers, which showed no evidence of fatigue or preexisting cracks.