NTSB Identification: CHI84IA264.
The docket is stored on NTSB microfiche number 26895.
Scheduled 14 CFR UNITED AIRLINES
Incident occurred Tuesday, June 26, 1984 in CHICAGO, IL
Probable Cause Approval Date: 08/30/1994
Aircraft: McDonnell Douglas DC-8-54, registration: N8048U
Injuries: 3 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.

DURING THE LANDING ROLL, THE LEFT MAIN GEAR SWIVEL LINK PIN FAILED ALLOWING THE REAR SET OF TIRES TO BECOME DETACHED FROM THE MAIN STRUT AND DRAG ALONG THE RWY. THE LEFT MAIN GEAR BOGIE WAS LAST OVERHAULED IN 1981. AT THE TIME OF FAILURE, IT HAD 4459 HOURS SINCE OVERHAUL. METALLURGICAL STUDY OF THE SWIVEL PIN REVEALED, 1) INTERGRANULAR CRACKING THRU 40% OF PIN CROSS-SECTION, 2) EVIDENCE OF STRESS CORROSION FROM OVERTORQUING THE NUT ON THREADED END OF PIN, 3) TRACES OF COPPER, SOMETIMES USED BEFORE CHROMIUM PLATING DURING OVERHAUL, FOUND IN CRACK, 4) NO OVERLOAD EVIDENCE IN PREEXISTANT CRACK, AND 5) INDICATIONS THAT FINAL FRACTURE WAS DUE TO OVERLOAD.

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

MAINTENANCE..IMPROPER..PILOT IN COMMAND

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

LANDING GEAR,MAIN GEAR ATTACHMENT..OVERTORQUE

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

LANDING GEAR,MAIN GEAR ATTACHMENT..STRESS CORROSION

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

LANDING GEAR,MAIN GEAR ATTACHMENT..FAILURE,TOTAL

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