NTSB Identification: CHI88LA014.
The docket is stored on NTSB microfiche number 40015.
Accident occurred Saturday, October 31, 1987 in LAPEER, MI
Probable Cause Approval Date: 06/07/1989
Aircraft: ENSTROM F-28A, registration: N9583
Injuries: 2 Uninjured.

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 HELICOPTER WAS IN CRUISE FLT WHEN THE RGT SIDE HORIZONTAL STABILIZER ATTACH TUBE FAILED & SEPARATED FROM THE TAIL BOOM, THEN CONTACTED THE TAIL ROTOR. THIS RESULTED IN FAILURE OF THE TAIL ROTOR DRIVE SHAFT FLEX COUPLING AT THE TAIL ROTOR GEAR BOX. IN TURN, THERE WAS A LOSS OF TAIL ROTOR THRUST. THE PLT MADE A SUCCESSFUL AUTOROTATION IN AN OPEN FIELD. AN EXAM OF THE RGT HORIZONTAL STABILIZER ATTACH TUBE REVEALED IT HAD FAILED FROM FATIGUE AT THE RGT INBOARD ATTACH HOLE. THE FATIGUE ORIGINATED AT A SURFACE DEFECT ON THE OUTER DIAMETER OF THE TUBE WHICH WAS CAUSED BY MISALIGNED DRILLING.

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

STABILIZER..FATIGUE

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

MAINTENANCE,INSTALLATION..IMPROPER..OTHER MAINTENANCE PERSONNEL

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

STABILIZER..SEPARATION


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