NTSB Identification: CHI01IA102.
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Scheduled 14 CFR AMERICAN AIRLINES INC
Incident occurred Tuesday, March 06, 2001 in Montreal, Canada
Probable Cause Approval Date: 11/01/2001
Aircraft: Fokker F28 MK 0100, registration: N1426A
Injuries: 44 Uninjured.

NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.

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.'"

The National Transportation Safety Board determines the probable cause(s) of this incident to be:

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.

Full narrative available

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