Trans State Airlines Flight 440
British Aerospace BAE JETSTREAM 3201 BAE JETSTR · Incident: total loss of engine power (mechanical failure) on approach
From St. Louis Lambert International Airport (STL) to University of Illinois Willard Airport (CMI)
Event
- NTSB case
- CHI95IA286
- 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
British Aerospace BAE JETSTREAM 3201 BAE JETSTR
- Aircraft type
- British Aerospace BAE JETSTREAM 3201
- 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
- N425AM
- Operator
- Trans State Airlines
- Onboard fatalities
- Unknown
- Route
- From St. Louis Lambert International Airport (STL), ST LOUIS, MOTo University of Illinois Willard Airport (CMI)
- 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
- Approach
- 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
- Total loss of engine power (mechanical 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
- Engine assembly, gear › Fatigue
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The airplane sustained minor damage following an uncontained failure of the number two engine during approach. The crew received a fire indication of the number two engine. They secured the engine and discharged the nacelle fire extinguishing system. They landed and evacuated the airplane without further incident. Examination revealed several penetrations of the right fuselage side and number two cowling. The gearbox housing had a hole at the 12 o'clock position in the plane of rotation of the helical drive (bull) gear. The combustion plenum had a hole at the five o'clock position. Fragments of the bull gear were recovered from within the gear box. Metallurgical examination of the bull gear revealed a fatigue crack that emanated from the root radius of a gear tooth. The crack progressed to an area of the fracture that contained 'features typical of overstress separation.' The hole in the combustion plenum was attributed to excessive temperature. No other metallurgical anomaly was noted.
Probable cause
fatigue cracking and subsequent catastrophic failure of the number two engine helical drive (bull) gear, which resulted in an overtemperature condition, bursting of the combustion plenum, and a subsequent in-flight fire.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CHI95IA286
- Event ID
- 20001207X04181
- Case number
- CHI95IA286
- 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: 2730eadaa67a767bc08ebf76519ecbde16cd73721cfb585d6be7fb6cdb2b10d4; retrieved 2026-09-18T17:58:00.110Z.