WITH FUEL TEMP GOING BELOW THE MINIMUM LIMIT; A WARMER ALT IS REQUESTED. AFTER A LONG DELAY WITH FUEL TEMP CONTINUING TO DECREASE; DSCNT IS BEGUN WITHOUT CLRNC.

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WHILE AT FL390; CREW NOTED TEMP AT -70 DEGS C (FORECAST TO BE -61 DEGS C). FUEL TANK TEMPS WERE AT -32 DEGS C. CREW CONTINUOUSLY MONITORED FUEL TANK TEMPS. WHEN FUEL REACHED -33 DEGS C; CREW REQUESTED LOWER ALT AND WAS CLRED TO FL370. FUEL TEMP REMAINED AT -33 DEGS C. CREW REQUESTED LOWER ALT AND WAS TOLD TO STAND BY. (NOTE: FUEL TEMP WAS GIVEN TO ATC FOR REASON.) SLIGHT SPD INCREASES HAD NO EFFECT ON FUEL TEMP. FREQ CHANGE WAS MADE TO GANDER OCEANIC PER REQUEST. CREW AGAIN REQUESTED LOWER ALT DUE TO FUEL TEMPS. CREW ADVISED TO STAND BY. FUEL TEMP WENT TO -34 DEGS C AND FUEL FLOW IN #1 ENG BEGAN FLUCTUATING. CAPT MADE DECISION TO DSND. AREA WAS CLRED VISUALLY AND WITH TCASII. CAPT ADVISED GANDER OF DSCNT AND ACFT WAS LEVELED AT FL275 ON PLANNED COURSE. DURING DSCNT; GANDER WAS NOT RESPONDING TO OUR RADIO CALLS (VHF) AND INFO OF OUR STATUS WAS RELAYED THROUGH ANOTHER ACFT ON FREQ. WE ESTABLISHED (VHF) COMS WITH GANDER AND ADVISED THEM OF OUR STATUS. WE WERE CLRED TO FL270 AND THE FLT CONTINUED WITHOUT INCIDENT. DUE TO COLDER THAN FORECAST TEMPS; THE REQUEST FOR LOWER ALTS PERHAPS SHOULD HAVE BEEN CONVEYED SOONER. HOWEVER; NEITHER THE CAPT NOR MYSELF HAD EXPERIENCED FUEL TEMPS THIS LOW ALONG THIS RTE OF FLT DURING PREVIOUS TRIPS.