Aircraft equipment problem. Fire warning.

Attributes
ACN	311837
Time
Date	199507
Day	Sat
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : rjtg
State Reference	FO
Altitude	msl bound lower : 33000 msl bound upper : 33000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : rjtg
Operator	common carrier : air carrier
Make Model Name	B747-100
Operating Under FAR Part	Part 121
Flight Phase	cruise other
Route In Use	enroute : other oceanic enroute : pacific
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 160 flight time total : 18000
ASRS Report	311837
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : declared emergency none taken : unable
Consequence	Other
Supplementary
Primary Problem	Aircraft

Narrative:

False fire warning. Flight from anc to narita during first hour experienced fault in detection loop B. Then 2 hours out of narita we had a fire warning with both nacelle indicators going full hot. The detector fault light illuminated on system-a but not system-B. Engine shutdown and fire procedure was done and fire bottle discharged. Emergency was declared and normal approach and landing made. We suspected possible electrical faults but did procedures for safety. Warnings were erratic. Maintenance found a decal shorting both a and B loops.

Original NASA ASRS Text

Title: ACFT EQUIP PROB. FIRE WARNING.

Narrative: FALSE FIRE WARNING. FLT FROM ANC TO NARITA DURING FIRST HR EXPERIENCED FAULT IN DETECTION LOOP B. THEN 2 HRS OUT OF NARITA WE HAD A FIRE WARNING WITH BOTH NACELLE INDICATORS GOING FULL HOT. THE DETECTOR FAULT LIGHT ILLUMINATED ON SYS-A BUT NOT SYS-B. ENG SHUTDOWN AND FIRE PROC WAS DONE AND FIRE BOTTLE DISCHARGED. EMER WAS DECLARED AND NORMAL APCH AND LNDG MADE. WE SUSPECTED POSSIBLE ELECTRICAL FAULTS BUT DID PROCS FOR SAFETY. WARNINGS WERE ERRATIC. MAINT FOUND A DECAL SHORTING BOTH A AND B LOOPS.

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.