As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ENGINE FIRE L RED CAS: AT FL310 RED L ENG FIRE LIGHT BEGAN TO FLICKER THEN FLASH AND THEN SOLID FOLLOWED BY ENG FIRE L CAS. AFTERWARS RECEIVED AMBER FIRE DETECT FAIL L CAS. THE SEQUENCE REPEATED AT LEAST TWICE THEN CLEARED AS WE DESCENDED. CORRECTIVE ACTION: REMOVED PCB NZ105 PNZ 7468182-1 SN 31266516-1. AND INSTALLED NEW PCB NZ105 PN 7468182-1 SN 32218412-3 PER CE-700 AMM 24-60-11