Narrative:

On flight from sat-pit, as we started our cruise at 37000', we started getting the equipment cooling fan light from the electrical and equipment compartment to flicker. We switched fans to the alternate position as required in our manual. About another 1/2 hour went by and the light stayed on. There was no procedure so we called company in mem for instructions from maintenance in pit. They didn't now what to do, so we decided to download nonessential equipment. I turned off the #2 and #3 navigation equipment and #3 communication, then the INS's. The gyros and FMC's both then failed to operate, so I put INS back in att, but no help. At this pint we had lost all navigation except DME and RMI, so I called ATC for vectors until we could straighten things out. He asked if we would like an emergency descent to mem,but I said no (maintenance also) because WX was good in pit and things were stable at cruise west/O having to make an emergency descent with no gyros to mem. We checked the book and found the correct procedure and page in the FMC to align the INS in att and then we got back (light went out) the #1 and navigation and gyro and proceeded to pit for a normal landing where the FAA met the plane and asked why we didn't land at mem. Also they asked about our communication failure and I said we didn't lose any communications, but when I checked with company, I turned ATC down when done on #2 and heard someone calling on that radio. So I checked with center because I thought I was losing the communications due to heat. I called the maintenance manager to put a new procedure in our book on realigning the FMC and for equipment cooling lights stays on.

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Original NASA ASRS Text

Title: IN CRUISE AT FL370 ELECTRIC COMPARTMENT OVERHEAT LIGHT CAME ON, FLICKERED, STAYED ON. FLT CREW REDUCED ELECTRIC LOAD AND INADVERTENTLY LOST NAVIGATION EQUIPMENT. LANDED AT DESTINATION WITHOUT INCIDENT AFTER RECOVERING BASIC NAVIGATION EQUIPMENT.

Narrative: ON FLT FROM SAT-PIT, AS WE STARTED OUR CRUISE AT 37000', WE STARTED GETTING THE EQUIP COOLING FAN LIGHT FROM THE ELECTRICAL AND EQUIP COMPARTMENT TO FLICKER. WE SWITCHED FANS TO THE ALTERNATE POS AS REQUIRED IN OUR MANUAL. ABOUT ANOTHER 1/2 HR WENT BY AND THE LIGHT STAYED ON. THERE WAS NO PROC SO WE CALLED COMPANY IN MEM FOR INSTRUCTIONS FROM MAINT IN PIT. THEY DIDN'T NOW WHAT TO DO, SO WE DECIDED TO DOWNLOAD NONESSENTIAL EQUIP. I TURNED OFF THE #2 AND #3 NAV EQUIP AND #3 COM, THEN THE INS'S. THE GYROS AND FMC'S BOTH THEN FAILED TO OPERATE, SO I PUT INS BACK IN ATT, BUT NO HELP. AT THIS PINT WE HAD LOST ALL NAV EXCEPT DME AND RMI, SO I CALLED ATC FOR VECTORS UNTIL WE COULD STRAIGHTEN THINGS OUT. HE ASKED IF WE WOULD LIKE AN EMER DSNT TO MEM,BUT I SAID NO (MAINT ALSO) BECAUSE WX WAS GOOD IN PIT AND THINGS WERE STABLE AT CRUISE W/O HAVING TO MAKE AN EMER DSNT WITH NO GYROS TO MEM. WE CHKED THE BOOK AND FOUND THE CORRECT PROC AND PAGE IN THE FMC TO ALIGN THE INS IN ATT AND THEN WE GOT BACK (LIGHT WENT OUT) THE #1 AND NAV AND GYRO AND PROCEEDED TO PIT FOR A NORMAL LNDG WHERE THE FAA MET THE PLANE AND ASKED WHY WE DIDN'T LAND AT MEM. ALSO THEY ASKED ABOUT OUR COM FAILURE AND I SAID WE DIDN'T LOSE ANY COMS, BUT WHEN I CHKED WITH COMPANY, I TURNED ATC DOWN WHEN DONE ON #2 AND HEARD SOMEONE CALLING ON THAT RADIO. SO I CHKED WITH CENTER BECAUSE I THOUGHT I WAS LOSING THE COMS DUE TO HEAT. I CALLED THE MAINT MGR TO PUT A NEW PROC IN OUR BOOK ON REALIGNING THE FMC AND FOR EQUIP COOLING LIGHTS STAYS ON.

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.