What was found
LOG PAGE WRITE UP IS AS FOLLOWS, RT ENG FIRE LIGHT ON APPROACH & LANDING, STAYED ON AFTER ENG SHUTDOWN. INSPECTED THE ENG FOR ANY SIGNS OF FIRE & FOUND NONE. THE FIRE WARNING LIGHT REMAINED LIT DURING INSPECTION. FOLLOWING THE TROUBLESHOOTING GUIDE IN THE AMM CH 26-10-01, WE FOUND THE LOWER FWD OPTICAL FIRE DETECTOR DID NOT HAVE THE PROPER GND SIGNAL. THE PART HAS BEEN ORDERED AT THIS POINT, PN 30-215-8 & SN 2365W. THE DEFECTIVE LOWER FWD OPTICAL FIRE DETECTOR UNIT WAS R & R WITH A NEW UNIT, PN 30-215-8 & SN 6811 ON AML 2124. NEW UNIT CORRECTED THE ISSUE & ACFT WAS RETURNED TO SERVICE.