NTSB Identification: LAX90LA186.
The docket is stored on NTSB microfiche number 52859.
Accident occurred Wednesday, May 23, 1990 in LA VERNE, CA
Probable Cause Approval Date: 01/31/1994
Aircraft: HUGHES 269A, registration: N8793F
Injuries: 2 Minor.

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

THE PILOT HAD BEEN ASKED BY THE OPERATOR TO FLY THE HELICOPTER PRIOR TO THE OPERATORS SIGNING A LEASEBACK AGREEMENT WITH THE REPORTED OWNER. THE INITIAL AIR TAXI TO A HELIPAD WAS ABORTED WHEN THE HELICOPTER BEGAN TO OSCILLATE DURING A GROUND RESONANCE EVENT. PRIOR TO THIS ATTEMPT THE OLEO STRUTS APPEARED TO BE OF EQUAL EXTENSION. AFTER THE EVENT, THE OLEO STRUTS WERE LOW AND ONE WAS FLAT. ABOUT 18 DAYS LATER, AND AFTER THE PILOT HAD BEEN TOLD THAT THE STRUTS HAD BEEN TAKEN CARE OF AND THAT THE OWNER HAD BEEN FLYING THE HELICOPTER AFTER A PLANNED AIR TAXI TO A HELIPAD. THE HELICOPTER AGAIN EXPERIENCED A GROUND RESONANCE EVENT WITH SEVERE OSCILLATIONS TO THE POINT OF DESTRUCTION. THE PILOT SAID HE LOWERED THE COLLECTIVE AND DECREASED THE THROTTLE WHEN THE OSCILLATIONS BEGAN. ATTEMPTS TO OBTAIN THE MAINTENANCE RECORDS AND COMPONENTS OF THE HELICOPTER FOR TESTING WERE UNSUCCESSFUL.

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

GROUND RESONANCE DUE TO AN INADEQUATELY MAINTAINED STRUT.

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