Narrative:

In cruise en route from cak to cvg at FL200 passing over cmh, the 'gear bay overheat' aural, the triple chime and main landing gear bay overheat warning message appeared. The first officer began to slow the aircraft to 250 KTS, while I retrieved the QRH. At 250 KTS the gear was lowered and having completed the memory items for a main landing gear bay overheat message I consulted the QRH. As the message remained on the EICAS, the QRH led to 'land at nearest suitable airport.' at which point I contacted ATC, advised them of the emergency and our intent to land at cmh. We were immediately cleared to cmh via radar vectors, starting with a left turn and given a descent to 11000 ft. The first officer began the descent. We notified the flight attendant, I called dispatch utilizing company radio, and dispatch notified the columbus station of our arrival. I then made a brief PA to the passenger explaining the unplanned landing in columbus. We were beginning the approach for runway 28L in columbus within about 5 mins of declaring the emergency. On downwind for the approach, however, the main landing gear bay overheat warning message had extinguished and was replaced by the main landing gear overheat fail caution message. During our arrival into columbus, we did explain that we had some doubt that the warning was a legitimate one as the system had just been replaced by maintenance in cak delaying our departure for 4 hours or so. The brake temperature monitoring system also indicated 01 01 01 01 (01 for each main gear brake, a cool indication). This indication was noted immediately upon lowering the gear, indicating that there was probably no overheat. The fact that the warning message had also gone to a 'fail' caution message by landing indicated that the system may have been faulty. I also gave a final call to the flight attendant on final, to make sure that she was comfortable and let her know that she need not brace, as I was unsure if we discussed it earlier in the fast pace of the initial descent. I also told her that the emergency vehicles were standing by but we really didn't expect to need them (reasoning that the system was probably faulty, as it had been worked on for hours. The brake temperature monitoring system were all in the green even with the overheat warning and that at this point the warning was gone and a caution indicating a system failure was all that remained). I elected to taxi to the gate upon landing while the emergency vehicle followed, rather than have then inspect the aircraft on or just clearing the runway. They followed us to the gate, where the inspection yielded no abnormal indications.

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Original NASA ASRS Text

Title: CL65 FLT CREW HAS A LNDG GEAR OVERHEAT WARNING WHILE ENRTE, DECLARES AN EMER AND DIVERTS TO CMH.

Narrative: IN CRUISE ENRTE FROM CAK TO CVG AT FL200 PASSING OVER CMH, THE 'GEAR BAY OVERHEAT' AURAL, THE TRIPLE CHIME AND MAIN LNDG GEAR BAY OVERHEAT WARNING MESSAGE APPEARED. THE FO BEGAN TO SLOW THE ACFT TO 250 KTS, WHILE I RETRIEVED THE QRH. AT 250 KTS THE GEAR WAS LOWERED AND HAVING COMPLETED THE MEMORY ITEMS FOR A MAIN LNDG GEAR BAY OVERHEAT MESSAGE I CONSULTED THE QRH. AS THE MESSAGE REMAINED ON THE EICAS, THE QRH LED TO 'LAND AT NEAREST SUITABLE ARPT.' AT WHICH POINT I CONTACTED ATC, ADVISED THEM OF THE EMER AND OUR INTENT TO LAND AT CMH. WE WERE IMMEDIATELY CLRED TO CMH VIA RADAR VECTORS, STARTING WITH A L TURN AND GIVEN A DSCNT TO 11000 FT. THE FO BEGAN THE DSCNT. WE NOTIFIED THE FLT ATTENDANT, I CALLED DISPATCH UTILIZING COMPANY RADIO, AND DISPATCH NOTIFIED THE COLUMBUS STATION OF OUR ARR. I THEN MADE A BRIEF PA TO THE PAX EXPLAINING THE UNPLANNED LNDG IN COLUMBUS. WE WERE BEGINNING THE APCH FOR RWY 28L IN COLUMBUS WITHIN ABOUT 5 MINS OF DECLARING THE EMER. ON DOWNWIND FOR THE APCH, HOWEVER, THE MAIN LNDG GEAR BAY OVERHEAT WARNING MESSAGE HAD EXTINGUISHED AND WAS REPLACED BY THE MAIN LNDG GEAR OVERHEAT FAIL CAUTION MESSAGE. DURING OUR ARR INTO COLUMBUS, WE DID EXPLAIN THAT WE HAD SOME DOUBT THAT THE WARNING WAS A LEGITIMATE ONE AS THE SYS HAD JUST BEEN REPLACED BY MAINT IN CAK DELAYING OUR DEP FOR 4 HRS OR SO. THE BRAKE TEMP MONITORING SYS ALSO INDICATED 01 01 01 01 (01 FOR EACH MAIN GEAR BRAKE, A COOL INDICATION). THIS INDICATION WAS NOTED IMMEDIATELY UPON LOWERING THE GEAR, INDICATING THAT THERE WAS PROBABLY NO OVERHEAT. THE FACT THAT THE WARNING MESSAGE HAD ALSO GONE TO A 'FAIL' CAUTION MESSAGE BY LNDG INDICATED THAT THE SYS MAY HAVE BEEN FAULTY. I ALSO GAVE A FINAL CALL TO THE FLT ATTENDANT ON FINAL, TO MAKE SURE THAT SHE WAS COMFORTABLE AND LET HER KNOW THAT SHE NEED NOT BRACE, AS I WAS UNSURE IF WE DISCUSSED IT EARLIER IN THE FAST PACE OF THE INITIAL DSCNT. I ALSO TOLD HER THAT THE EMER VEHICLES WERE STANDING BY BUT WE REALLY DIDN'T EXPECT TO NEED THEM (REASONING THAT THE SYS WAS PROBABLY FAULTY, AS IT HAD BEEN WORKED ON FOR HRS. THE BRAKE TEMP MONITORING SYS WERE ALL IN THE GREEN EVEN WITH THE OVERHEAT WARNING AND THAT AT THIS POINT THE WARNING WAS GONE AND A CAUTION INDICATING A SYS FAILURE WAS ALL THAT REMAINED). I ELECTED TO TAXI TO THE GATE UPON LNDG WHILE THE EMER VEHICLE FOLLOWED, RATHER THAN HAVE THEN INSPECT THE ACFT ON OR JUST CLRING THE RWY. THEY FOLLOWED US TO THE GATE, WHERE THE INSPECTION YIELDED NO ABNORMAL INDICATIONS.

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.