Boeing 737-222 incident near Chicago, Illinois, April 7, 1995
On April 7, 1995 at about 10:10 pm local time, a Boeing 737-222, registered N9090U, suffered minor damage in an incident near Chicago, Illinois (O'Hare Int'L Airport). It was a flight of an unrecorded kind under scheduled airline rules (Part 121). No one was hurt; 116 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
the inadequacy or deterioration of lubricating grease in the wheel bearing, which led to the total bearing failure and subsequent loss of the wheel. Factors were the insufficiently defined procedures for repacking the bearing, along with an insufficient method of retaining lubricant within the bearing.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- April 7, 1995 · about 10:10 pm local time
- Place
- Chicago, Illinois · O'Hare Int'L Airport
- Type
- Incident
- Injuries
- No one was hurt; 116 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Boeing 737-222 · all 737-222s on the register
- Registration
- N9090U · no longer on the register · serial 19078
- Damage
- Minor damage
- Flight
- Flight of an unrecorded kind · scheduled airline rules (Part 121)
The NTSB's narrative final · quoted from the NTSB record
THE LEFT OUTBOARD MAIN WHEEL SEPARATED FROM THE AIRPLANE ON TAKEOFF. THE AIRPLANE WAS LANDED WITHOUT FURTHER INCIDENT. INVESTIGATION REVEALED THAT THE OUTER BEARING FAILED. HEAT AND MECHANICAL DAMAGE WERE CONSISTENT WITH INADEQUATE LUBRICATION. PRE-EXISTING MECHANICAL DAMAGE COULD NOT BE DETERMINED. THE WHEEL BEARING HAD ACCUMULATED 349 LANDING CYCLES SINCE INITIAL INSTALLATION, AND 219 CYCLES SINCE A BRAKE CHANGE. IT COULD NOT BE CONFIRMED THAT THE BEARING HAD BEEN REPACKED WITH GREASE SINCE INITIAL INSTALLATION. AN UNKNOWN QUANTITY OF GREASE HAD MIGRATED AWAY FROM THE BEARING CAVITY DURING OPERATION. AVERAGE CYCLES BETWEEN 737-200 WHEEL CHANGES PERFORMED BY THE OPERATOR WERE 259, AND WORLDWIDE ACCORDING TO BOEING WERE 200. AN OPTIONAL OUTER GREASE SEAL TO RETAIN GREASE WITHIN THE BEARING WAS NOT INSTALLED. THE BEARING AND WHEEL ASSEMBLY MANUFACTURERS STATED THAT AFTER 150 CYCLES, LUBRICATION PROPERTIES OF GREASE RAPIDLY DEGRADE.
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
Pilot
- Certificate: airline transport pilot, flight instructor
- Ratings: multi-engine land; single-engine land; instructor: airplane multi-engine; instructor: airplane single-engine; instrument: airplane
- Flight time: 5,564 hours in all; 3,368 in this make and model
- Medical certificate: Class 1 (valid medical--no waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 51,274 hours
- Last inspection: continuous airworthiness programme, November 24, 1994; 794 hours since
- Maximum gross weight: 117,000 lb
- Seats: 117
- Landing gear: retractable
- Engine: P&W JT8D-7B (turbojet); 0 hours total
The flight
- Destination: ATL Atlanta GA
- Flight plan: IFR
- Runway 9L, 7,967 ft by 150 ft
- A second pilot was aboard
Weather at the time
- Light: daylight
- Wind: from 040° at 16 knots
- Visibility: 4 statute miles
- Sky: overcast at 1,500 ft; not recorded
- Temperature: 43°F (6°C), dew point 37°F (3°C)
- Altimeter: 29.00 inHg
- Observation at 9:52 pm from ORD
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 5 | |||
| Passengers | 111 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
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 never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.