NTSB Identification: ATL93IA111.
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Incident occurred Tuesday, June 15, 1993 in CULLMAN, AL
Probable Cause Approval Date: 05/17/1994
Aircraft: SIKORSKY S-76A, registration: N110AL
Injuries: 5 Uninjured.
NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.
THE PILOT REPORTED THAT DURING CRUISE FLIGHT, AT ABOUT 200 FEET AGL, HE HEARD A 'SNAP' SOUND, AND THE HELICOPTER YAWED ABOUT 30 DEGREES TO THE RIGHT. HE OBSERVED THE LEFT ANTITORQUE PEDAL TO BE INOPERATIVE. DIRECTIONAL CONTROL WAS MAINTAINED WITH ENGINE POWER ADJUSTMENTS. A RUN ON LANDING WAS PERFORMED AT THE BIRMINGHAM AIRPORT. THE HELICOPTER WAS THEN TOWED FROM THE RUNWAY. AN INSPECTION OF HELICOPTER REVEALED THAT THE LEFT TAIL ROTOR CABLE ASSEMBLY HAD FAILED IN THE VICINITY OF A PULLEY. METALLURGICAL EXAMINATION INDICATED THAT THE CABLE FAILED FROM SEVERE WEAR OF THE INDIVIDUAL WIRES OF THE CABLE STRANDS. THE CABLE WAS INSPECTED 521 HOURS PRIOR TO THE INCIDENT; MAINTENANCE MANUAL DICTATES CABLE INSPECTION AT EVERY 750 HOUR INSPECTION. CABLE WAS ORIGINAL EQUIPMENT ON THIS HELICOPTER (4110 HRS TOTAL TIME).
The National Transportation Safety Board determines the probable cause(s) of this incident to be: THE FAILURE OF COMPANY MAINTENANCE PERSONNEL TO PROPERLY INSPECT THE TAIL ROTOR CONTROL CABLE AT THE LAST 750 HOUR INSPECTION, AND THE SUBSEQUENT TOTAL FAILURE OF THE CABLE DUE TO WEAR. Full narrative available
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