Air Wisconsin Fokker F-27 MK500 incident
Fokker F-27 MK500 · Incident: main gear collapsed during landing
From Chicago O'Hare International Airport (ORD) to an unrecorded destination
Event
- NTSB case
- CHI89IA084
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Incident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- 0
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- Airline
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Fokker F-27 MK500
- Aircraft type
- Fokker F-27
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N511AW
- Operator
- Air Wisconsin
- Onboard fatalities
- Unknown
- Route
- From Chicago O'Hare International Airport (ORD), Chicago, ILTo not recorded
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 121: Air Carrier
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Landing · flare/touchdown
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Main gear collapsed
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Minor
Cause areas
- Company/operator management › Maintenance, inspection, inadequate
- Landing gear, normal retraction/extension assembly › Binding(mechanical)
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
THE AIRPLANE LANDED WITH THE RIGHT MAIN LANDING GEAR NOT FULLY DOWN AND LOCKED. WHEN THE AIRPLANE TOUCHED DOWN, THE LANDING GEAR WOULD NOT SUPPORT THE WEIGHT OF THE AIRPLANE AND IT COLLAPSED. THE AIRPLANE SUSTAINED MINOR DAMAGE AND NEITHER OF THE TWO CREWMEMBERS ABOARD THE AIRPLANE WERE INJURED. THE LANDING GEAR MALFUNCTION HAD BEEN DISCOVERED WHEN THE LANDING GEAR WOULD NOT CYCLE PROPERLY DURING A MAINTENANCE CHECK FLIGHT. WHEN THE FLIGHT CREW ATTEMPTED TO LOWER THE LANDING GEAR AFTER RETRACTION, THE RIGHT MAIN LANDING GEAR WOULD NOT FULLY EXTEND. ATTEMPTS TO EXTEND THE LANDING GEAR USING EMERGENCY PROCEDURES WERE NOT SUCCESSFUL.
Probable cause
MATERIAL FAILURE OF THE LANDING GEAR RETRACTION AND EXTENSION ASSEMBLY. INADEQUATE MAINTENANCE AND TROUBLESHOOTING PROCEDURES IN COMPANY DIRECTIVES WERE FACTORS IN THIS INCIDENT.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CHI89IA084
- Event ID
- 20001213X28264
- Case number
- CHI89IA084
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: local date, investigation status. Values present in the bulk record are kept.
- The date is the local date; the NTSB stores the UTC date 1989-05-04.
- API snapshot SHA-256: 6d4b5e507cdb504c5bedae833046e8543ee4ac7880f310e086496c51cbb756a0; retrieved 2026-09-18T19:12:10.613Z.