Serious incident McDonnell Douglas MD-83 N931AS, Sunday 17 April 1994

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Date:	Sunday 17 April 1994
Time:	19:55 LT
Type:	McDonnell Douglas MD-83
Owner/operator:	Alaska Airlines
Registration:	N931AS
MSN:	49232/1178
Year of manufacture:	1985
Total airframe hrs:	25773 hours
Engine model:	P&W JT8D-217A
Fatalities:	Fatalities: 0 / Occupants: 139
Other fatalities:	0
Aircraft damage:	Minor
Category:	Serious incident
Location:	Seattle, WA - United States of America
Phase:	Taxi
Nature:	Unknown
Departure airport:	San Francisco, CA (SFO
Destination airport:
Investigating agency:	NTSB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
DURING THE LANDING/TAXI SEQUENCE, THE LEFT MAIN GEAR WHEEL HUB EXPERIENCED A FATIGUE FRACTURE. THE CRACKS WHICH LED TO THE FRACTURE ORIGINATED IN THE HUB GREASE DAM GROOVE. THE FRACTURING OF THE HUB DAMAGED OTHER BRAKE COMPENENTS, WHICH ALLOWED HYDRAULIC FLUID TO LEAK ONTO A HOT BRAKE PAD, WHERE IT WAS IGNITED.

Probable Cause: THE FATIGUE FRACTURE OF A MAIN GEAR WHEEL HUB.

Accident investigation: