NTSB Identification: CHI02FA148.
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Scheduled 14 CFR Northwest Airlines, Inc.
Accident occurred Monday, June 03, 2002 in Minneapolis, MN
Probable Cause Approval Date: 11/25/2003
Aircraft: Douglas DC-9-31, registration: N8986E
Injuries: 70 Uninjured.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
During landing rollout the right main landing gear (RMLG) collasped. The captain reported a normal landing was completed by the first officer and when he took over control of the airplane "the aircraft dropped sharply to the right and we began skidding down the runway with a continous warning horn. I continued braking and the aircraft came to a stop on centerline with a significant right lean." According to the NTSB Materials Laboratory Factual Report, the outer cylinder of the RMLG was fractured through the transition area above the fused section, with the fracture located approximately 19 inches from the upper end of the cylinder. The factual report noted the fracture initiation point "lies in the parting plane for the cylinder forging. The dark spot [fracture initiation point] was orientated transverse to the gear about 28 7/8 inches from the lower end of the cylinder." According to the factual report, multiple inclusions and intergranular cracks were uncovered within the examined fracture sample. The inclusions were mostly oxides of aluminum and calcium and some inclusions contained small sulfides of iron and manganese. The report noted there were fracture features that were consistent with overstress separation "emanating from the dark spot [fracture initiation point] with mostly ductile dimple formations and some cleavage like features."
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The failure of the right main landing gear due to fatigue. Full narrative available
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