Serious incident Boeing 727-223 N6821, Thursday 3 January 1991

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Date:	Thursday 3 January 1991
Time:	20:30 LT
Type:	Boeing 727-223
Owner/operator:	American Airlines
Registration:	N6821
MSN:	19496/669
Year of manufacture:	1968
Engine model:	P&W JT8D-9
Fatalities:	Fatalities: 0 / Occupants: 104
Other fatalities:	0
Aircraft damage:	None
Category:	Serious incident
Location:	Des Moines, IA - United States of America
Phase:	Taxi
Nature:	Unknown
Departure airport:	Dallas/Fort Worth International Airport, TX (DFW/KDFW)
Destination airport:
Investigating agency:	NTSB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
THE AIRPLANE WAS TAXIING TO ITS ASSIGNED GATE AFTER LANDING WHEN A FLIGHT ATTENDENT INFORMED THE CAPTAIN THAT THERE WAS A FIRE IN THE REAR OF THE AIRPLANE. THE CAPTAIN IMMEDIATELY STOPPED AND THE PASSENGERS WERE DEPLANNED USING THE COMPANY'S EMERGENCY EVACUATION PROCEDURES. A FLIGHT ATTENDENT AND ONE PASSENGER RECEIVED MINOR INJURIES DURING THE EVACUATION PROCESS. NINETH-SIX PASSENGERS AND SIX OTHER AIRPLANE CREWMEMBERS DID NOT RECEIVE INJURIES. A FIRE WAS NOT PRESENT, SMOKE HAD BEEN FILLING THE PASSENGER CABIN. THE SMOKE CAME FROM THE AIR CONDITIONING/HEATING SYSTEM DUCTS. THE SMOKE WAS A RESULT OF AN OIL LEAK IN THE AIRCRAFT POWER UNIT (APU) WHICH ENTERED THE APU DUCT WORK, THE AIR CONDITIONING PACKS AND ASSOCIATED CIRCULATION DUCTING. WHEN A CERTAIN HEAT RANGE HAD BEEN SELECTED THE OIL LADEN AIR WOULD CHANGE INTO SMOKE AS IT EXITED THE CABIN HEAT DUCT OPENING.

Probable Cause: AN OIL LEAK ORIGINATING FROM THE AUXILIARY POWER UNIT WHICH CREATED SMOKE IN THE PASSENGER CABIN AFTER IT PASSED THROUGH THE AIR CONDITIONING/HEATING SYSTEM EQUIPMENT AND ASSOCIATED DUCT WORK.

Accident investigation: