An A320 had an APU fire warning while parked at the gate with the APU off and the aft cargo door ope...

Narrative:

We had a false APU fire warning after APU shutdown. We had already completed the parking checklist; and I was up out of my seat greeting departing passengers. I heard the warning buzzer in the nose wheel well sound; and turned to see a red fire light illuminated in the APU emergency shutoff switch. The APU was already shut down; and the captain had selected ground power. I was surprised that there was no repetitive warning bell for fire; but in the press of events I thought it was due to the plane being on battery power (which it was not). The ECAM screens were already off for the night. The captain activated the emergency shutoff switch; and I advocated discharging the fire bottle; since the light was still illuminated. He called ground and I called station operations to summon the fire trucks. I went to the cockpit door and determined that most of the passengers had deplaned or were forward and on their way out. With the captain's concurrence; I ran outside to get the baggage handlers out of the rear cargo pit and away from the airplane while we awaited the fire trucks. I saw no evidence of a fire; and initial analysis by the mechanics pointed to a failed warning relay that had triggered a false fire warning. I was initially confused by the indications because the ECAM screens were secured; but if they had been on I'm not sure I'd have done anything differently. Even if I suspected a false warning; I think the prudent thing to do would be to honor it and discharge the bottle. I was also somewhat tired at this later hour in my domicile time; and didn't immediately realize that we were not getting all the correct indications of an APU fire appropriate to our current electrical configuration. I am familiar with the airbus-specific issue of false cargo pit fire ecams on the ground with cargo doors open; and of course would not have responded to that situation with a fire bottle discharge.

Original NASA ASRS Text

Title: An A320 had an APU fire warning while parked at the gate with the APU OFF and the aft cargo door open so fire fighting procedures were followed but fire fighters found no fire.

Narrative: We had a false APU fire warning after APU shutdown. We had already completed the parking checklist; and I was up out of my seat greeting departing passengers. I heard the warning buzzer in the nose wheel well sound; and turned to see a red fire light illuminated in the APU emergency shutoff switch. The APU was already shut down; and the Captain had selected ground power. I was surprised that there was no repetitive warning bell for fire; but in the press of events I thought it was due to the plane being on battery power (which it was not). The ECAM screens were already off for the night. The Captain activated the emergency shutoff switch; and I advocated discharging the fire bottle; since the light was still illuminated. He called ground and I called station operations to summon the fire trucks. I went to the cockpit door and determined that most of the passengers had deplaned or were forward and on their way out. With the Captain's concurrence; I ran outside to get the baggage handlers out of the rear cargo pit and away from the airplane while we awaited the fire trucks. I saw no evidence of a fire; and initial analysis by the mechanics pointed to a failed warning relay that had triggered a false fire warning. I was initially confused by the indications because the ECAM screens were secured; but if they had been on I'm not sure I'd have done anything differently. Even if I suspected a false warning; I think the prudent thing to do would be to honor it and discharge the bottle. I was also somewhat tired at this later hour in my domicile time; and didn't immediately realize that we were not getting all the correct indications of an APU fire appropriate to our current electrical configuration. I am familiar with the Airbus-specific issue of false cargo pit fire ECAMS on the ground with cargo doors open; and of course would not have responded to that situation with a fire bottle discharge.

Data retrieved from NASA's ASRS site as of April 2012 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	930817
Time
Date	201101
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	A320
Operating Under FAR Part	Part 121
Flight Phase	Parked
Flight Plan	IFR
Component
Aircraft Component	APU Fire/Overheat Warning
Person 1
Function	Pilot Flying
Experience	Flight Crew Last 90 Days 175 Flight Crew Total 12000 Flight Crew Type 8600
Person 2
Function	Pilot Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 230 Flight Crew Total 21500 Flight Crew Type 6500
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Published Material / Policy

An A320 had an APU fire warning while parked at the gate with the APU off and the aft cargo door open so fire fighting procedures were followed but fire fighters found no fire.