Boeing 737 incident near Chicago, Illinois, October 1, 2008
On October 1, 2008 at about 4:55 pm local time, a Boeing 737, registered N551WN, suffered minor damage in an incident during taxi (from runway) near Chicago, Illinois (Chicago Midway airport). It was flown under scheduled airline rules (Part 121). No one was hurt; 133 people were on board or involved.
The NTSB's probable cause their words, unchanged
The right nose landing gear axle's failure from intergranular and fatigue cracking due to an earlier bearing failure.
Source: NTSB aviation accident database, copy made October 12, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- October 1, 2008 · about 4:55 pm local time · cases in 2008
- Place
- Chicago, Illinois · Chicago Midway · cases near this airport · map
- Type
- Incident
- Injuries
- No one was hurt; 133 people were on board or involved.
- Weather
- not recorded
- Aircraft
- Boeing 737 -76Q · all 737s on the register
- Registration
- N551WN · no longer on the register · serial 30280
- Damage
- Minor damage
- Flight
- Flight · scheduled airline rules (Part 121)
The NTSB's narrative final · quoted from the NTSB record
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.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
What happened, in order
- Aircraft structural failure during taxi (from runway)
- Landing gear collapse during taxi (from runway) defining event
The NTSB's findings
- cause Aircraft › Aircraft systems › Landing gear system › Nose/tail landing gear › Failure other cases naming the landing gear
- cause Aircraft › Aircraft systems › Landing gear system › Nose/tail landing gear › Fatigue/wear/corrosion other cases naming the landing gear
The aircraft
- Airframe total time: 21,206 hours
- Last inspection: continuous airworthiness programme; 3 hours since
- Maximum gross weight: 154,000 lb
- Seats: 145
- Landing gear: retractable
- Engine: Cfm CFM56-7B22 (turbofan); 0 hours total
- Operator: Southwest Airlines, Co.
The flight
- Departed from: MCI Kansas City MO at 2:43 pm
- Destination: MDW Chicago IL
- Flight plan: IFR
- Runway 31C, 6,522 ft by 150 ft
- A second pilot was aboard
Weather at the time
- Temperature: 0°F (-18°C), dew point 0°F (-18°C)
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Cabi | 3 | |||
| Flight crew | 2 | |||
| Passengers | 128 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
3 documents, released by the NTSB on October 20, 2009. View them here, or download them; the NTSB redacts some personal details before release, and this site shows the NTSB's own titles rather than its file names.
| # | Document | What it is | |
|---|---|---|---|
| 1 | Materials Laboratory 15 - Factual Report 09-044 | PDF, 15 pages | View Download |
| 2 | Flight Data Recorder 10 - Specialist's Factual Report | PDF, 5 pages | View Download |
| 3 | Flight Data Recorder 10 - Attachment 1 (Tabular FDR Data) | data file | Download |
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
Other NTSB records under N551WN the same tail number, which may have belonged to a different aircraft at the time
Connections how this case links to the rest of the register
- N551WN: not on the register today · the record of its deregistration
- Boeing 737 2,894 registered today · the model family and its accident history
- Boeing 6,676 aircraft on the register
- Engine: Cfm CFM56-7B22 35 aircraft carry this series today · as the NTSB recorded it
- Chicago Midway International · nearest airport
- Kansas City International · departed from
- Accidents and incidents in Illinois 2,117 since 1982 · 250 in the last ten years
- Illinois 8,055 aircraft registered
- Other NTSB records under N551WN 1 records · the number may have belonged to another aircraft at the time
The whole map of how records connect · these connections as data: /graph/accident/ENG08IA042.json.
The bigger picture in Aviation Analytics: accidents over time since 1982, by model, by phase of flight and conditions, by place and on the map.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text does not name anyone involved, its policy at this time. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.