Eastern Air Lines Douglas DC-9-31 incident
Douglas DC-9-31 · Incident: airframe, component or system failure during landing
From General Mitchell International Airport (MKE) to Louisville Muhammad Ali International Airport (SDF)
Event
- NTSB case
- ATL90IA060
- 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
Douglas DC-9-31
- Aircraft type
- Douglas DC-9
- 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
- N8978E
- Operator
- Eastern Air Lines
- Onboard fatalities
- Unknown
- Route
- From General Mitchell International Airport (MKE), Milwaukee, WITo Louisville Muhammad Ali International Airport (SDF)
- 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 · landing roll
- 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
- Airframe, component or system failure
- 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
- Landing gear, main gear strut scissors › Disabled
- Production/design personnel › Inadequate quality control
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
AFTER LANDING THE FLIGHT CREW NOTED A VIBRATION. LEFT MAIN GEAR TORQUE LINK APEX BOLT WAS FOUND TO HAVE VIBRATED OUT OF THE TORQUE LINK WHICH ALLOWED MAIN GEAR TRUCK TO ROTATE 360 DEGREES DURING LANDING ROLL. THE NUT HAD STRIPPED OFF OF THE BOLT. LABORATORY EXAMINATION REVEALED THAT THE TORQUE LINK ATTACHING PINS HAD EXCESSIVE PLAY. NEW & OLD APEX BOLTS WERE MEASURED. THEY FAILED TO PASS THE MOST STRINGENT QUALITY CONTROL CHECK FOR CORRECT THREAD SIZE. THE SAFETY BOARD BELIEVES THAT THE NUT STRIPPED OFF WHEN THE LOOSE TORQUE LINKS ALLOWED EXCESSIVE VIBRATION. THE UNDERSIZE APEX BOLT THREADS ALLOWED THE NUT TO SHEAR AWAY THE BOLT PIN DESIGNED TO RETAIN THE NUT.
Probable cause
THE DISABLING OF THE MAIN LANDING GEAR TORQUE LINK WHICH ALLOWED THE TRUCK TO ROTATE FREELY. THE TORQUE LINK WAS DISABLED WHEN EXCESSIVE VIBRATION WAS GENERATED BY EXCESSIVE PLAY OF THE TORQUE LINK PINS IN THEIR BUSHINGS.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ATL90IA060
- Event ID
- 20001212X22363
- Case number
- ATL90IA060
- 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: investigation status. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: d217e0e8d35a518dc2d2f280bda653093f23fbdded39fdbb69f91ff2190aa3f8; retrieved 2026-09-18T19:05:05.136Z.