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American Airlines Flight 581

6 Mar 2001 · Montreal, Canada

Fokker F28 MK 0100 · Incident: airframe, component or system failure while standing

From Montreal / Pierre Elliott Trudeau International Airport (YUL) to Chicago O'Hare International Airport (ORD)

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Event

NTSB case
CHI01IA102
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

Fokker F28 MK 0100

Aircraft type
Fokker F28
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
N1426A
Onboard fatalities
Unknown
Route
From Montreal / Pierre Elliott Trudeau International Airport (YUL), MontrealTo 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
Standing · engine(s) operating
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

  • Auxiliary power unit › Failure
  • Ground personnel › Aircraft service, inaccurate

Approximate · Estimated position: the centre of Montréal, the place the record names. Not the accident site.

NTSB narrative

The auxiliary power unit (APU) ingested deicing fluid and snow and sustained an uncontained turbine failure. The pressure bulkhead sustained minor damage. The airplane was being deiced. Four crew and 40 passengers were uninjured. The YUL weather was: Wind 050 degrees at 25 knots gusting to 33 knots; visibility 15 statute miles; present weather drifting snow; sky condition broken 2,800 feet overcast 7,600 feet; temperature -1 degree C; dew point -5 degrees C; altimeter 29.57 inches of mercury. Honeywell's APU teardown inspection stated, "Evidence of an engine overspeed event with a commanded auto-shutdown was present in the Electronic Control Unit (ECU) non-volatile memory." The report further stated, "In February 2001 American Airlines issued a 'Winterization Bulletin' for the F-100 advising that de-ice spray should not be sprayed into the APU inlet. Additionally, the Fokker 100 maintenance manual section 12-31-00, page 301specifically advises 'Do not let de-icing and/or anti-icing fluid/water mixture go into the APU inlet. Injury to persons and/or damage to equipment can occur.'"

Probable cause

the inaccurate aircraft deicing service the ground personnel performed alowing fluid injestion and the auxiliary power unit's turbine failure while standing. A factor was the auxiliary power unit's overspeed.

Verbatim NTSB analysis and probable cause from the NTSB dataset

Sources

NTSB record CHI01IA102
Event ID
20010316X00598
Case number
CHI01IA102
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. 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: 7a38bfac6045e6153ab29e123dbd15339f2da4d3b85713df9cad3f9f66a56931; retrieved 2026-09-18T16:16:10.732Z.
  • The NTSB's operator name is blank for N1426A; the operator shown is the name the NTSB's other records give its FAA operator code, AALA.