As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MAIN CARGO FIRE MASTER WARNING INDICATION DURING PRE-FLIGHT W/MAIN CARGO LOOP 2 STATUS MESSAGE. TROUBLESHOT IAW WDM 26-16-31, AND SSM 26-16-03. FOUND A BAD DETECTOR AT POSITION 2C2E. REMOVED AND REPLACED THE DETECTOR IAW AMM 26-14-01. OPS CHECKED GOOD IAW AMM 26-14-00.