Return land mandated by fire warning in cargo bay of a b- 747 freighter.

Attributes
ACN	300549
Time
Date	199503
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : ort
State Reference	AK
Altitude	msl bound lower : 33000 msl bound upper : 33000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zan
Operator	common carrier : air carrier
Make Model Name	B747-100
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	cruise other other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 10000
ASRS Report	300549
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:

Aircraft, a 747-2A freighter, on an IFR flight plan, anc-ord. Approximately 1 hour after takeoff, in cruise at FL330, had a main deck fire warning. The light stayed on for approximately 5 mins, then extinguished. A crewmember examined the main deck cargo, no smoke or fire detected, but possible fumes, very faint. Flight returned to anc. Aircraft dumped 30000 pounds fuel to reduce landing weight. Fuel dumped during descent from FL330 to FL190. After landing, no evidence of fire/smoke. Fire detectors replaced without further incident.

Original NASA ASRS Text

Title: RETURN LAND MANDATED BY FIRE WARNING IN CARGO BAY OF A B- 747 FREIGHTER.

Narrative: ACFT, A 747-2A FREIGHTER, ON AN IFR FLT PLAN, ANC-ORD. APPROX 1 HR AFTER TKOF, IN CRUISE AT FL330, HAD A MAIN DECK FIRE WARNING. THE LIGHT STAYED ON FOR APPROX 5 MINS, THEN EXTINGUISHED. A CREWMEMBER EXAMINED THE MAIN DECK CARGO, NO SMOKE OR FIRE DETECTED, BUT POSSIBLE FUMES, VERY FAINT. FLT RETURNED TO ANC. ACFT DUMPED 30000 LBS FUEL TO REDUCE LNDG WT. FUEL DUMPED DURING DSCNT FROM FL330 TO FL190. AFTER LNDG, NO EVIDENCE OF FIRE/SMOKE. FIRE DETECTORS REPLACED WITHOUT FURTHER INCIDENT.

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.