What was found
CARGO FIRE LOOP FAULT DURING TAXI OUT. COMPLIED WITH QRH. SMOKE LIGHT ILLUMINATED. SHUTDOWN ACFT. RAN EVACUATION CHECKLIST. FIRE DEPARTMENT DETECTED NO HOTSPOTS WITH IR. NO ODOR IN COURIER COMPARTMENT. ENGINE RESTART FOR RETURN TO RAMP. THEN RECEIVED A MID 1 LOOP A FAULT. NO SMOKE LIGHT ASSOCIATED. RETURNED TO RAMP. REMOVED AND INSPECTED THE SMOKE DETECTORS. NO EVIDENCE OF DAMAGE OR CONTAMINATION. INSPECTED AIR TUBES FOR SECURITY AND GOOD AIRFLOW. INSPECTED AIR INLET FILTERS. NO OILY FILM FOUND ON ANY OF THE FILTERS OR LINES. FOUND DEBRIS FROM DUST AND LINT ON FILTERS. CLEANED DEBRIS FROM THE FILTERS IAW AMM 26-19-13-06. PERFORMED OPS TEST OF MAIN DECK CARGO SMOKE DETECTION SYS IAW AMM 26-19-00-5.