NTSB Identification: CHI95TA243.
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Accident occurred Thursday, July 27, 1995 in KANSAS CITY, MO
Probable Cause Approval Date: 06/07/1996
Aircraft: Schweizer 300C, registration: N643KC
Injuries: 1 Minor.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this public aircraft accident report.

The pilot reported that he made a normal, smooth landing. He said the helicopter had been on the ground about 5 to 6 seconds and that he had reduced the engine rpm back between 2700 and 2800 RPM's, when he noticed a vibration in the helicopter. The pilot said he rolled in the throttle to 3100 rpm and attempted to get the helicopter into a hover. He reported that the vibrations were severe, and about one second later, the left skid collapsed and the main rotor contacted the tailboom. He secured and evacuated the helicopter after all motion had stopped. Tests revealed that the charge pressure for all four landing gear dampers was lower than that specified by the maintenance instructions. The maintenance instructions warned that improper shock strut pressure levels may result in ground resonance and destruction of the helicopter. Examination of the main rotor head dampers revealed no evidence of preexisting cracks or fatigue.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

ground resonance as a result of improper servicing of the main landing gear dampers.

Full narrative available

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