American Airlines Flight 1163
Boeing 757-223 · Incident: airframe, component or system failure while taxiing
From Miami International Airport (MIA) to Chicago O'Hare International Airport (ORD)
Event
- NTSB case
- MIA03IA168
- 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
- Unknown
- 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
Boeing 757-223
- Aircraft type
- Boeing 757
- 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
- N609AA
- Operator
- American Airlines
- Onboard fatalities
- Unknown
- Route
- From Miami International Airport (MIA), Miami, FLTo Chicago O'Hare International Airport (ORD), Chicago, IL
- 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
- Taxi · to runway
- 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
- Company maintenance personnel › Maintenance, inspection, inadequate
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The first officer stated that during preflight examination of the airplane he didn't see anything wrong with the aircraft and it was deemed suitable for flight. During taxi, the airplane suddenly dipped left and skidded to a stop. The flightcrew assessed a possible tire blowout and after contacting ground control the aircraft behind them confirmed it was the left outboard main tire and that it was smoking. Airport emergency authorities responded and noted the left main landing gear had failed. The authorities observed no smoke or fire. Maintenance personnel confirmed that the bogie on the left main gear had failed. The left main landing gear truck beam had fractured in two pieces between the aft axle and the truck pivot pin. There was no truck beam shield present with the wreckage although the attach straps were present. The fracture occurred about 14 inches forward of the aft axle centerline. Metallurgical analysis revealed the fracture of the truck beam was the result of stress corrosion cracking (SCC). The SCC was precipitated by damage to the protective finishes on the lower surface of the beam. The material of the beam is very susceptible to SCC at the high strengths specified. It is vitally important to maintain the protective finishes and prevent exposure of the base material to atmospheric conditions when loaded. According to operator, the landing gear was delivered new with the airplane on July 29, 1996 and had accumulated 7,517 cycles since new. There was no truck beam shield present with the wreckage although the attach straps were present. The Boeing 757 configuration deviation list (CDL), which was current at the time of the incident, lists items that can be missing for flight. The main landing gear truck beam shields may be missing for flight. There was no requirement to inspect the landing gear for damage prior to dispatch with a truck beam shield missing. Maintenance personnel had not identified the missing truck beam shield on the left main landing gear of the airplane and the shield was not on the current list of missing items under the CDL.
Probable cause
The failure of maintenance personnel from the aircraft operator to identify a missing left main landing gear truck beam shield and damage to the left main landing gear truck beam which resulted in the fracture of the truck beam as a result of stress corrosion cracking.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record MIA03IA168
- Event ID
- 20030827X01408
- Case number
- MIA03IA168
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (5)
- 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, coordinates. 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: 1ee1cff3bd2281c5a57c6cdb66b0daca6a5b7c4008e1df986c916941eb4bb9e5; retrieved 2026-09-18T15:41:39.985Z.
- The NTSB's operator name is blank for N609AA; the operator shown is the name the NTSB's other records give its FAA operator code, AALA.