Medium large transport has APU fire warning activate on taxi out.

Attributes
ACN	247973
Time
Date	199307
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : den
State Reference	CO
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	ground other : taxi
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 180 flight time total : 10000 flight time type : 1000
ASRS Report	247973
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Shortly after starting to taxi from den to runway 35R, an APU fire warning light/bell occurred. We stopped the aircraft as we pulled the fire handle and discharged the extinguisher bottle. We asked tower if they could see smoke or fire at tail of aircraft as we lowered flaps in preparation for an evacuate/evacuation. They said 'no smoke.' we asked for the fire trucks and declared an emergency. The APU fire light went out (about 30 seconds after bottle fired) and all reports from flight attendants and tower indicated no fire or smoke. We decided not to evacuate/evacuation and returned to gate and deplaned passenger. Although intense effort made to get us on way to msp as soon as possible, I insisted on an interior inspection of APU compartment and it was determined that electrical short had occurred. Redispatched and departure uneventful.

Original NASA ASRS Text

Title: MLG HAS APU FIRE WARNING ACTIVATE ON TAXI OUT.

Narrative: SHORTLY AFTER STARTING TO TAXI FROM DEN TO RWY 35R, AN APU FIRE WARNING LIGHT/BELL OCCURRED. WE STOPPED THE ACFT AS WE PULLED THE FIRE HANDLE AND DISCHARGED THE EXTINGUISHER BOTTLE. WE ASKED TWR IF THEY COULD SEE SMOKE OR FIRE AT TAIL OF ACFT AS WE LOWERED FLAPS IN PREPARATION FOR AN EVAC. THEY SAID 'NO SMOKE.' WE ASKED FOR THE FIRE TRUCKS AND DECLARED AN EMER. THE APU FIRE LIGHT WENT OUT (ABOUT 30 SECONDS AFTER BOTTLE FIRED) AND ALL RPTS FROM FLT ATTENDANTS AND TWR INDICATED NO FIRE OR SMOKE. WE DECIDED NOT TO EVAC AND RETURNED TO GATE AND DEPLANED PAX. ALTHOUGH INTENSE EFFORT MADE TO GET US ON WAY TO MSP ASAP, I INSISTED ON AN INTERIOR INSPECTION OF APU COMPARTMENT AND IT WAS DETERMINED THAT ELECTRICAL SHORT HAD OCCURRED. REDISPATCHED AND DEP UNEVENTFUL.

Data retrieved from NASA's ASRS site as of July 2007 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.