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| Date: | Wednesday 1 October 2008 |
| Time: | 10:55 LT |
| Type: |  Boeing 737-76Q |
| Owner/operator: | Southwest Airlines |
| Registration: | N551WN |
| MSN: | 30280/1025 |
| Year of manufacture: | 2001 |
| Total airframe hrs: | 21206 hours |
| Engine model: | CFMI CFM56-7B22 |
| Fatalities: | Fatalities: 0 / Occupants: 133 |
| Other fatalities: | 0 |
| Aircraft damage: | Minor |
| Category: | Serious incident |
| Location: | Chicago-O'Hare International Airport, IL (ORD/KORD) -
 United States of America
|
| Phase: | Taxi |
| Nature: | Passenger - Scheduled |
| Departure airport: | Kansas City International Airport, MO (MCI/KMCI) |
| Chicago-Midway Airport, IL (MDW/KMDW) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The airplane experienced separation of the right nose landing gear (NLG)wheel assembly as it exited runway after landing. Metallurgical examination revealed that the NLG axle fractured in a transverse plane, and that the failure of the axle was due to intergranular cracking that acted as stress concentrators from which fatigue cracks emanated. The fracture of the right side inboard journal on the NLG inner cylinder assembly was most likely due to the failure of a prior tapered roller bearing. Eventually the size of the fatigue crack and the forces generated during landing were sufficient to drive the crack in overstress, leading to fracture of the inboard journal. The change in ownership of the plane and the monthly swapping of bearings and wheels make it difficult to determine when the bearing failure occurred or why.
Probable Cause: The right nose landing gear axle's failure from intergranular and fatigue cracking due to an earlier bearing failure.
Accident investigation:
 |
|
Sources:
NTSB ENG08IA042
History of this aircraft
Other occurrences involving this aircraft
| 22 February 2008 | N551WN | Southwest Airlines | 0 | Valdosta, GA | |
non |
| Turbulence | ||||||
| 18 March 2023 | N551WN | Southwest Airlines | 0 | Hollywood Burbank Airport, CA (BUR/KBUR) | |
non |
| Runway incursion with a/c (no oollision) | ||||||
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 25-Mar-2024 08:10 | ASN Update Bot | Added |
Corrections or additions? ... Edit this accident description
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