An A321 APU had an apparent tail pipe fire after shutdown so the crew used the APU P/B to close the ...

Narrative:

Arrived at gate. Ground power was established while passengers were deplaning. APU was then shut down. Immediately thereafter lots of commotion outside. First officer opened his window to hear what ground personnel were saying. Apparently flames were shooting out of the APU with lots of smoke. This continued for nearly a minute; yet we had no indication of an APU fire on the overhead fire panel. After some discussion; first officer and I decided that at the very least we should shut off the APU's source of fuel; so I pushed its fire P/B but did not discharge an agent through the APU. Normally an APU would shut itself down and discharge a bottle on its own if a true fire was sensed. In this case; the fire warning system did not sense a fire yet there was some sort of abnormal tail-pipe fire associated with the APU. Operations; maintenance; and airport crash fire rescue were called. Every fire truck in all the county showed up but the fire and smoke had dissipated by the time they arrived. No visible external evidence of fire could be seen after the event. Maintenance took possession of the aircraft.

Original NASA ASRS Text

Title: An A321 APU had an apparent tail pipe fire after shutdown so the crew used the APU P/B to close the fuel and called the Fire Department.

Narrative: Arrived at gate. Ground power was established while passengers were deplaning. APU was then shut down. Immediately thereafter lots of commotion outside. First Officer opened his window to hear what ground personnel were saying. Apparently flames were shooting out of the APU with lots of smoke. This continued for nearly a minute; yet we had no indication of an APU fire on the overhead fire panel. After some discussion; First Officer and I decided that at the very least we should shut off the APU's source of fuel; so I pushed its fire P/B but did not discharge an agent through the APU. Normally an APU would shut itself down and discharge a bottle on its own if a true fire was sensed. In this case; the fire warning system did not sense a fire yet there was some sort of abnormal tail-pipe fire associated with the APU. Operations; Maintenance; and Airport Crash Fire Rescue were called. Every fire truck in all the county showed up but the fire and smoke had dissipated by the time they arrived. No visible external evidence of fire could be seen after the event. Maintenance took possession of the aircraft.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1059699
Time
Date	201301
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Make Model Name	A321
Operating Under FAR Part	Part 121
Flight Phase	Parked
Flight Plan	IFR
Component
Aircraft Component	APU
Person 1
Function	Pilot Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Critical Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor Ground Event / Encounter Other / Unknown

An A321 APU had an apparent tail pipe fire after shutdown so the crew used the APU P/B to close the fuel and called the fire department.