What was found
PDX - ON APPROACH TO PDX IN IMC FIRE BELL AND NR 1 ENGINE T-HANDLE ILLUM. PROCEEDED WITH IAC UPON SECURING NR 1 ENGINE T-HANDLE LIGHT EXTINGUISHED. ABOUT 1 MINUTE AFTER SECURING NR 1 ENGINE, NR 1 T-HANDLE INDICATION AND FIRE BELL RE-ILLUMINATED. FIRED EXTINGUISHERS, T-HANDLE INDICATION EXTINGUISHED WITH 2ND FIRE BOTTLE. REQUESTED CFR, LANDED WITHOUT INCIDENT, NO INDICATION OF FIRE FOUND UPON INSPECTION. REPLACED PEC, FIRE LOOP, FIRE BOTTLES, FADEC, CVR, FDR, GENERATOR,VALVES, CARTRIDGE, AND RESTRICTOR. CHECKED GOOD. A/C RETURNED TO SERVICE. THE FINAL FIX WAS DETERMINED TO BE BAD PEC FIRE LOOP. FIRE LOOP TRIPED AT 160 DEG F INSTEAD OF 300 DEG F.