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ASN Wikibase Occurrence # 203061
Last updated: 1 April 2020
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Time:11:15 UTC
Type:Silhouette image of generic A333 model; specific model in this crash may look slightly different
Airbus A330-323
Owner/operator:American Airlines
Registration: N276AY
C/n / msn: 375
Fatalities:Fatalities: 0 / Occupants: 291
Other fatalities:0
Aircraft damage: None
Location:London Heathrow Airport (LHR/EGLL) -   United Kingdom
Phase: Standing
Nature:International Scheduled Passenger
Departure airport:London Heathrow Airport (LHR/EGLL)
Destination airport:Charlotte-Douglas International Airport, NC (CLT/KCLT)
Investigating agency: AAIB
The cabin of American Airlines Flight 731 filled with smoke whilst the aircraft was on stand at London Heathrow Airport after boarding. The cabin crew were unsuccessful in making contact with the commander, and one of the flight attendants (FAs) initiated a passenger evacuation.
Several passengers exited using the emergency slides from the two aft doors, but most left using the jetbridge at exit 2L. Passengers opened the two emergency exits situated immediately aft of the wings (exit 3L and exit 3R). Exit 3L had not been armed, so the slides did not deploy and the passengers did not use the exit. Exit 3R was armed and opened by a passenger and the slide deployed, but this exit was not used either.
The commander attempted to halt the evacuation, (because he believed he had isolated the source of the smoke) which caused some confusion until the FAs encouraged all remaining passengers to exit via the jetbridge.
Air Traffic Control (ATC) observed the incident and alerted the emergency services, which reached the scene quickly. Three passengers and several FAs received treatment for the effects of smoke inhalation and one passenger suffered a minor leg injury while using an escape slide.

Smoke entered the cabin after the APU load compressor oil seal became compromised, allowing hot oil to enter and pyrolyse in the bleed air supply to the cabin. Examination of the APU after the event revealed considerable metallic debris in its shared oil system. This debris eventually caused the load compressor carbon seal to fail, allowing hot oil to enter the bleed air supply to the cabin and causing smoke in the cabin. The initiating source of the debris could not be identified positively due to the distribution of debris throughout the oil system.

This emergency situation, involving an evacuation from an aircraft parked at the gate with the jetbridge in place, was unusual for the FAs, who had not practised it as part of the aircraft operator’s training programme. Prompt and effective communication between the cabin and the flight deck might have avoided an evacuation, but the pilots and the IRO were distracted by the presence of an engineer, who was attending to a defect. The normal interphone call function used by the cabin crew did not attract their attention.



Safety recommendations:

Safety recommendation 2017-022 issued by AAIB to FAA
Safety recommendation 2017-023 issued by AAIB to EASA
Safety recommendation 2017-024 issued by AAIB to FAA
Safety recommendation 2017-025 issued by AAIB to EASA
Safety recommendation 2017-026 issued by AAIB to FAA
Safety recommendation 2017-027 issued by AAIB to FAA
Safety recommendation 2017-028 issued by AAIB to EASA
Safety recommendation 2017-029 issued by AAIB to FAA

Accident investigation:
Investigating agency: AAIB
Status: Investigation completed
Duration: 1 year and 5 months
Download report: Final report


Photo of N276AY courtesy

London - Heathrow (EGLL / LHR)
2 January 2017; (c) John Smitherman

Revision history:

17-Dec-2017 20:50 harro Added
18-Dec-2017 20:43 Dr. John Smith Updated [Source, Embed code, Narrative]
18-Dec-2017 20:44 Dr. John Smith Updated [Embed code, Narrative]

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