Narrative:

Fwd cargo fire light appeared. Accomplished checklists. Received descent clearance.supplemental information from acn 724212: at the gate in ZZZ2 we were informed that live bees with dry ice would be in the forward cargo pit; and that live dogs would be in the aft cargo pit. We also had the captain's radio tuning panel inoperative; which was deferred. Taxiing out it appeared the left VHF radio was stuck on 126.5 despite it being tuned to 120.5 on the right tuning panel. Climbing out we got a status message that read fwd cgo 1 lp B; and joked about the fact that it seemed the airplane was acknowledging one pound of bees in the forward pit. I had the other two fos run cargo fire suppression squib tests; and I ran 2 more fire tests with the fire/ovht button just to check that everything was working; or at least tested fine. At approximately XA25Z; we got a fwd cgo fire light and bells. The captain told me to run the qrc. I immediately armed the forward cargo area; and pushed the extinguisher button. The fire light went out after a while; and came on about 5 times total throughout the remainder of the flight; with intermittent equipment cooling EICAS messages. We contacted dispatch via satcom; and received outstanding support about the distances and WX at each station; and together we decided that ZZZ1 was the best choice; about 360 miles ahead at that point. We monitored the cargo temperature on the EICAS from seconds after the indication throughout the landing. Initially it was 69 degrees F; and it rose to no more than 75 degrees; and stabilized around 73 degrees. This suggested that either the fire suppression was effective; or that there never was a fire. The equipment cooling EICAS added more pieces to the puzzle. It came on two or three times as I recall; and we discussed doing the appropriate checklist. We elected not to do the equipment cooling checklist. My reasoning was that; since there is the equipment supply valve moving air from the forward cargo to the equipment; and the inboard exhaust valve moving air from the equipment to the forward cargo; it would be difficult to determine a cause-effect relationship between the cargo pit and the east&east bay. By doing nothing; and leaving the valves open; we were hopefully introducing extinguishing agent into the east&east bay if it was the source of any fire. If we isolated the east&east bay by going to ovrd; that would potentially let the fire grow in the east&east bay with no help from the extinguishing agent. The other concern with the east&east cooling issue was the potential to lose avionics as the situation progressed. We did in fact lose the captain's nd after landing. We sent a cpdlc message about our emergency; and asked for a descent to 5000 ft via HF. I wanted to descend low (5000 ft) to facilitate a ditching if it was necessary. The captain preferred 10;000 ft; presumably for VHF radio reception and VOR reception and terrain clearance. We descended to 10;000 ft; dumped fuel down to maximum landing weight; and reset the landing altitude switch to complete the cargo fire reference actions. The captain took the airplane during rollout and taxied to the apron with fire trucks in tow. We deplaned; allowing passenger to take their carryon luggage down the airstairs. We left the cargo pits closed until everyone was off the airplane. They may have been closed for an hour or more before opening. A horn was going off somewhere in the wheel well; so I went back to the cockpit to turn off the irss; thinking that may have been the cause of the horn. It turns out the horn was probably the horn related to fire warnings. It stayed on for several hours; until we could get airstairs back on the airplane and reset the arming switch for the forward cargo. The mechanic swapped out the captain's nd with the lower EICAS; giving the captain back a good display. Of course; the lower EICAS was blank now; but deferrable with the proper person legal to sign off the work. We had all the cargo pits unloaded so that we could take the passenger to destination legally without fire suppression in the cargo area. My biggest concern was the inability to properly analyze what the cause of our fire light was; or even whether it came from the east&east bay or the forward cargo pit. Some kind of camera or window to the pits would be nice. It would be nice to be able to manually fire the C and D fire bottles; if desired; rather than being stuck with the metering system which doesn't begin until 30 minutes after the a and B bottles were fired.callback conversation with reporter 724214 revealed the following information: reporter stated that because two separate smoke sensors are required to activate the cargo smoke/fire warning; he could only assume that the smoke/fire indication was actual and not a system malfunction. His air carrier's maintenance has not informed him of the maintenance investigation's outcome.

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Original NASA ASRS Text

Title: B747-400 FLT CREW HAS FIRE WARNING; DECLARES AN EMER AND DIVERTS FOR LNDG.

Narrative: FWD CARGO FIRE LIGHT APPEARED. ACCOMPLISHED CHKLISTS. RECEIVED DSCNT CLRNC.SUPPLEMENTAL INFO FROM ACN 724212: AT THE GATE IN ZZZ2 WE WERE INFORMED THAT LIVE BEES WITH DRY ICE WOULD BE IN THE FORWARD CARGO PIT; AND THAT LIVE DOGS WOULD BE IN THE AFT CARGO PIT. WE ALSO HAD THE CAPT'S RADIO TUNING PANEL INOP; WHICH WAS DEFERRED. TAXIING OUT IT APPEARED THE LEFT VHF RADIO WAS STUCK ON 126.5 DESPITE IT BEING TUNED TO 120.5 ON THE RIGHT TUNING PANEL. CLIMBING OUT WE GOT A STATUS MESSAGE THAT READ FWD CGO 1 LP B; AND JOKED ABOUT THE FACT THAT IT SEEMED THE AIRPLANE WAS ACKNOWLEDGING ONE POUND OF BEES IN THE FORWARD PIT. I HAD THE OTHER TWO FOS RUN CARGO FIRE SUPPRESSION SQUIB TESTS; AND I RAN 2 MORE FIRE TESTS WITH THE FIRE/OVHT BUTTON JUST TO CHECK THAT EVERYTHING WAS WORKING; OR AT LEAST TESTED FINE. AT APPROXIMATELY XA25Z; WE GOT A FWD CGO FIRE LIGHT AND BELLS. THE CAPT TOLD ME TO RUN THE QRC. I IMMEDIATELY ARMED THE FORWARD CARGO AREA; AND PUSHED THE EXTINGUISHER BUTTON. THE FIRE LIGHT WENT OUT AFTER A WHILE; AND CAME ON ABOUT 5 TIMES TOTAL THROUGHOUT THE REMAINDER OF THE FLT; WITH INTERMITTENT EQUIP COOLING EICAS MESSAGES. WE CONTACTED DISPATCH VIA SATCOM; AND RECEIVED OUTSTANDING SUPPORT ABOUT THE DISTANCES AND WX AT EACH STATION; AND TOGETHER WE DECIDED THAT ZZZ1 WAS THE BEST CHOICE; ABOUT 360 MILES AHEAD AT THAT POINT. WE MONITORED THE CARGO TEMPERATURE ON THE EICAS FROM SECONDS AFTER THE INDICATION THROUGHOUT THE LNDG. INITIALLY IT WAS 69 DEGS F; AND IT ROSE TO NO MORE THAN 75 DEGS; AND STABILIZED AROUND 73 DEGS. THIS SUGGESTED THAT EITHER THE FIRE SUPPRESSION WAS EFFECTIVE; OR THAT THERE NEVER WAS A FIRE. THE EQUIP COOLING EICAS ADDED MORE PIECES TO THE PUZZLE. IT CAME ON TWO OR THREE TIMES AS I RECALL; AND WE DISCUSSED DOING THE APPROPRIATE CHKLIST. WE ELECTED NOT TO DO THE EQUIP COOLING CHKLIST. MY REASONING WAS THAT; SINCE THERE IS THE EQUIP SUPPLY VALVE MOVING AIR FROM THE FORWARD CARGO TO THE EQUIP; AND THE INBOARD EXHAUST VALVE MOVING AIR FROM THE EQUIP TO THE FORWARD CARGO; IT WOULD BE DIFFICULT TO DETERMINE A CAUSE-EFFECT RELATIONSHIP BETWEEN THE CARGO PIT AND THE E&E BAY. BY DOING NOTHING; AND LEAVING THE VALVES OPEN; WE WERE HOPEFULLY INTRODUCING EXTINGUISHING AGENT INTO THE E&E BAY IF IT WAS THE SOURCE OF ANY FIRE. IF WE ISOLATED THE E&E BAY BY GOING TO OVRD; THAT WOULD POTENTIALLY LET THE FIRE GROW IN THE E&E BAY WITH NO HELP FROM THE EXTINGUISHING AGENT. THE OTHER CONCERN WITH THE E&E COOLING ISSUE WAS THE POTENTIAL TO LOSE AVIONICS AS THE SITUATION PROGRESSED. WE DID IN FACT LOSE THE CAPT'S ND AFTER LANDING. WE SENT A CPDLC MESSAGE ABOUT OUR EMER; AND ASKED FOR A DSCNT TO 5000 FT VIA HF. I WANTED TO DSND LOW (5000 FT) TO FACILITATE A DITCHING IF IT WAS NECESSARY. THE CAPT PREFERRED 10;000 FT; PRESUMABLY FOR VHF RADIO RECEPTION AND VOR RECEPTION AND TERRAIN CLRNC. WE DESCENDED TO 10;000 FT; DUMPED FUEL DOWN TO MAX LNDG WT; AND RESET THE LNDG ALT SWITCH TO COMPLETE THE CARGO FIRE REFERENCE ACTIONS. THE CAPT TOOK THE AIRPLANE DURING ROLLOUT AND TAXIED TO THE APRON WITH FIRE TRUCKS IN TOW. WE DEPLANED; ALLOWING PAX TO TAKE THEIR CARRYON LUGGAGE DOWN THE AIRSTAIRS. WE LEFT THE CARGO PITS CLOSED UNTIL EVERYONE WAS OFF THE AIRPLANE. THEY MAY HAVE BEEN CLOSED FOR AN HOUR OR MORE BEFORE OPENING. A HORN WAS GOING OFF SOMEWHERE IN THE WHEEL WELL; SO I WENT BACK TO THE COCKPIT TO TURN OFF THE IRSS; THINKING THAT MAY HAVE BEEN THE CAUSE OF THE HORN. IT TURNS OUT THE HORN WAS PROBABLY THE HORN RELATED TO FIRE WARNINGS. IT STAYED ON FOR SEVERAL HOURS; UNTIL WE COULD GET AIRSTAIRS BACK ON THE AIRPLANE AND RESET THE ARMING SWITCH FOR THE FORWARD CARGO. THE MECHANIC SWAPPED OUT THE CAPT'S ND WITH THE LOWER EICAS; GIVING THE CAPT BACK A GOOD DISPLAY. OF COURSE; THE LOWER EICAS WAS BLANK NOW; BUT DEFERRABLE WITH THE PROPER PERSON LEGAL TO SIGN OFF THE WORK. WE HAD ALL THE CARGO PITS UNLOADED SO THAT WE COULD TAKE THE PAX TO DEST LEGALLY WITHOUT FIRE SUPPRESSION IN THE CARGO AREA. MY BIGGEST CONCERN WAS THE INABILITY TO PROPERLY ANALYZE WHAT THE CAUSE OF OUR FIRE LIGHT WAS; OR EVEN WHETHER IT CAME FROM THE E&E BAY OR THE FORWARD CARGO PIT. SOME KIND OF CAMERA OR WINDOW TO THE PITS WOULD BE NICE. IT WOULD BE NICE TO BE ABLE TO MANUALLY FIRE THE C AND D FIRE BOTTLES; IF DESIRED; RATHER THAN BEING STUCK WITH THE METERING SYSTEM WHICH DOESN'T BEGIN UNTIL 30 MINUTES AFTER THE A AND B BOTTLES WERE FIRED.CALLBACK CONVERSATION WITH RPTR 724214 REVEALED THE FOLLOWING INFO: RPTR STATED THAT BECAUSE TWO SEPARATE SMOKE SENSORS ARE REQUIRED TO ACTIVATE THE CARGO SMOKE/FIRE WARNING; HE COULD ONLY ASSUME THAT THE SMOKE/FIRE INDICATION WAS ACTUAL AND NOT A SYSTEM MALFUNCTION. HIS ACR'S MAINT HAS NOT INFORMED HIM OF THE MAINT INVESTIGATION'S OUTCOME.

Data retrieved from NASA's ASRS site as of January 2009 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.