Narrative:

Aircraft had 1 maintenance item deferred: the #1 engine 'a' fire loop was deferred. Operate with #1 engine 'B' fire loop only. About 1500 ft on final to runway 23, ZZZ crew noticed the master caution and could just barely see the overheat light illuminated before both lights extinguished. We did not have time to see which system was affected. At 800 ft AGL, the lights reappeared and stayed illuminated. We saw that the #1 engine overheat light was illuminated. I told the PF to 'fly the plane' and I would work the problem. We confirmed #1 throttle and pulled to idle. We left the confign at flaps 30 degrees and continued to land. I declared an emergency at 500 ft AGL and told the tower to have the fire trucks meet me at the end of the runway. PF did a great job with the landing. On rollout, I saw the overheat light was still on, so I shut down the #1 engine. I took control of the plane about 80 KTS and exited the runway near the end. After clearing runway 23, I set the parking brake and directed the PNF to run the overheat and engine fire qrc. The fire trucks were at the #1 engine about the same time as we reached the step of firing the bottle. I was talking to the fire people and they said there was no evidence of an overheat. At that time I elected not to fire the bottle. Shortly after, the overheat light extinguished, so I had the fire trucks escort me to the gate. As we turned into the chocks the overheat light re-illuminated. All engine readings were normal with the #1 egt cooling down normally. I offloaded the passenger, called dispatch, facility operations dispatch manager, and operations. Even though we treated the problem like the engine was actually overheated, I feel it was an indication problem. Supplemental information from acn 639526: we were met by the crash fire rescue equipment within 30 seconds. During this time we had shut down the #1 engine and ran the appropriate checklists and started the APU. #1 egt was normal prior to shutdown, therefore, we elected to terminate the 'engine fire' checklist prior to 'engine fire handle...pull' and we did not discharge the fire bottle. The system was tested on the ground in ZZZ with the 'B' loop selected and operated normally during the flight prior to the incident. Both loops tested normally on the ground in ZZZ reinforcing that this was an intermittent problem.

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Original NASA ASRS Text

Title: B737-300 FLT CREW EXPERIENCES A #1 ENG OVERHEAT ON SHORT FINAL DURING A NIGHT OP ILS APCH RWY 23 AT ZZZ.

Narrative: ACFT HAD 1 MAINT ITEM DEFERRED: THE #1 ENG 'A' FIRE LOOP WAS DEFERRED. OPERATE WITH #1 ENG 'B' FIRE LOOP ONLY. ABOUT 1500 FT ON FINAL TO RWY 23, ZZZ CREW NOTICED THE MASTER CAUTION AND COULD JUST BARELY SEE THE OVERHEAT LIGHT ILLUMINATED BEFORE BOTH LIGHTS EXTINGUISHED. WE DID NOT HAVE TIME TO SEE WHICH SYS WAS AFFECTED. AT 800 FT AGL, THE LIGHTS REAPPEARED AND STAYED ILLUMINATED. WE SAW THAT THE #1 ENG OVERHEAT LIGHT WAS ILLUMINATED. I TOLD THE PF TO 'FLY THE PLANE' AND I WOULD WORK THE PROB. WE CONFIRMED #1 THROTTLE AND PULLED TO IDLE. WE LEFT THE CONFIGN AT FLAPS 30 DEGS AND CONTINUED TO LAND. I DECLARED AN EMER AT 500 FT AGL AND TOLD THE TWR TO HAVE THE FIRE TRUCKS MEET ME AT THE END OF THE RWY. PF DID A GREAT JOB WITH THE LNDG. ON ROLLOUT, I SAW THE OVERHEAT LIGHT WAS STILL ON, SO I SHUT DOWN THE #1 ENG. I TOOK CTL OF THE PLANE ABOUT 80 KTS AND EXITED THE RWY NEAR THE END. AFTER CLRING RWY 23, I SET THE PARKING BRAKE AND DIRECTED THE PNF TO RUN THE OVERHEAT AND ENG FIRE QRC. THE FIRE TRUCKS WERE AT THE #1 ENG ABOUT THE SAME TIME AS WE REACHED THE STEP OF FIRING THE BOTTLE. I WAS TALKING TO THE FIRE PEOPLE AND THEY SAID THERE WAS NO EVIDENCE OF AN OVERHEAT. AT THAT TIME I ELECTED NOT TO FIRE THE BOTTLE. SHORTLY AFTER, THE OVERHEAT LIGHT EXTINGUISHED, SO I HAD THE FIRE TRUCKS ESCORT ME TO THE GATE. AS WE TURNED INTO THE CHOCKS THE OVERHEAT LIGHT RE-ILLUMINATED. ALL ENG READINGS WERE NORMAL WITH THE #1 EGT COOLING DOWN NORMALLY. I OFFLOADED THE PAX, CALLED DISPATCH, FACILITY OPS DISPATCH MGR, AND OPS. EVEN THOUGH WE TREATED THE PROB LIKE THE ENG WAS ACTUALLY OVERHEATED, I FEEL IT WAS AN INDICATION PROB. SUPPLEMENTAL INFO FROM ACN 639526: WE WERE MET BY THE CFR WITHIN 30 SECONDS. DURING THIS TIME WE HAD SHUT DOWN THE #1 ENG AND RAN THE APPROPRIATE CHKLISTS AND STARTED THE APU. #1 EGT WAS NORMAL PRIOR TO SHUTDOWN, THEREFORE, WE ELECTED TO TERMINATE THE 'ENG FIRE' CHKLIST PRIOR TO 'ENG FIRE HANDLE...PULL' AND WE DID NOT DISCHARGE THE FIRE BOTTLE. THE SYS WAS TESTED ON THE GND IN ZZZ WITH THE 'B' LOOP SELECTED AND OPERATED NORMALLY DURING THE FLT PRIOR TO THE INCIDENT. BOTH LOOPS TESTED NORMALLY ON THE GND IN ZZZ REINFORCING THAT THIS WAS AN INTERMITTENT PROB.

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.