As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT ENGINE FIRE WARNING SYSTEM. AFTER BEGINNING DESCENT FROM 9,000 FEET IN HEAVY RAIN, THE LEFT ENGINE FIRE WARNING SYSTEM ACTIVATED. ANUNCIATOR REMAINED ILLUMINATED 2 TO 3 MINUTES AND THEN WENT BACK OFF ABOUT THE SAME TIME THE RAIN LIGHTENED UP. ANOTHER U21 OPERATOR HAS UNVERIFIED REPORT OF A FALSE FIRE WARNING DURING HEAVY RAIN CONDITIONS.