NTSB Identification: ANC93IA084.
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Incident occurred Sunday, June 06, 1993 in ANCHORAGE, AK
Probable Cause Approval Date: 09/26/1994
Aircraft: BOEING 737-200, registration: N673MA
Injuries: 2 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.

WHILE TAXIING OFF THE RUNWAY AT DILLINGHAM, ALASKA, THE FLIGHT CREW HEARD A 'POP' AND 'GRINDING' SOUND. THE AIRPLANE WAS SUBSEQUENTLY FERRIED TO ANCHORAGE WITH THE NOSE GEAR PINNED IN THE DOWN POSITION. UPON TOUCHDOWN IN ANCHORAGE, THE NOSE GEAR SEPARATED FROM THE AIRPLANE. A METALLURGICAL EXAMINATION OF THE AFFECTED COMPONENTS, PRIMARILY THE NOSE LANDING GEAR INNER CYLINDER, SHOWED THAT THE INNER CYLINDER HAD SEPARATED CLOSE TO THE LOWER END NEAR THE AXLES FOR THE TIRES. VISUAL EXAMINATION OF THE FRACTURE SURFACE WITH THE AID OF A BENCH BINOCULAR MICROSCOPE REVEALED FEATURES TYPICAL OF AN OVERSTRESS SEPARATION INCLUDING CHEVRON MARKS OVER THE MAJORITY OF THE FRACTURE SURFACE AND THE PRESENCE OF A 45 DEGREE FRACTURE PLANE. DURING THE PREVIOUS 12 MONTH PERIOD THERE WERE NO 'HARD' LANDINGS ON RECORD FOR THE AIRPLANE.

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

THE FAILURE OF THE NOSE LANDING GEAR INNER CYLINDER FROM AN OVERLOAD/OVERSTRESS CONDITION.

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