NTSB Identification: MIA88LA186.
The docket is stored on NTSB microfiche number 36531.
Accident occurred Wednesday, June 01, 1988 in CALLAHAN, FL
Probable Cause Approval Date: 07/21/1989
Aircraft: Continental Copters MK6B, registration: N9080T
Injuries: 1 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.

WHILE MANEUVERING THE HELICOPTER DURING AN AERIAL APPLICATION FLT THE ENG QUIT. DURING THE AUTOROTATIVE LANDING THE HELICOPTER LANDED HARD. EXAMINATION OF THE ENG REVEALED THE ACCESSORY DRIVE GEAR, WHICH IS ATTACHED TO THE CRANKSHAFT BY 6 AN-4A BOLTS WITH THE TORQUE TRANSMITTED TO THE GEAR THROUGH 3 PRESS-FIT DOWEL PINS, SEPARATED WHEN THE BOLTS FAILED DUE TO FATIGUE, RESULTING IN THE TOTAL LOSS OF ENG POWER. THERE WAS NO EVIDENCE THAT THE DOWEL PINS WERE INSTALLED. ACCORDING TO THE ENG MANUFACTURER, THE DOWEL PINS ARE THE PRINCIPAL TORQUE CARRYING MECHANISM OF THE ACCESSORY DRIVE GEAR.

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

ACCESSORY DRIVE ASSY,DRIVE GEAR..FATIGUE

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

ACCESSORY DRIVE ASSY,DRIVE GEAR..SEPARATION

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

MAINTENANCE,INSTALLATION..IMPROPER..OTHER MAINTENANCE PERSONNEL



Contributing Factors

FLARE..IMPROPER..PILOT IN COMMAND

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