As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NR 1 ENGINE A FIRE DETECTION LOOP FLUCTUATING (SPIKING INTO RED ZONE). TRANSFERRED TO DMI NR 257 IAW MEL 26-1 CAT C PLACARD INSTALLED. PERFORMED OPERATIONAL CHECK OF NR 1 ENG A LOOP, OPS CHECKS NORMAL ON GROUND. THIS CLEARS DMI 257, PLACARDS REMOVED.