As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) AFTER TAKEOFF, ENGINE NR 1 FIRE-WARNING ALARM WENT OFF. THE FLIGHT CREW INFORMED TOWER AND RETURNED TO AIRPORT. A HOLE WAS FOUND IN THE FLEXIBLE DUCT AT THE SUPERCHARGER OUTLET. ALSO, (2) FIRE DETECTION LOOPS WERE REPLACED BECAUSE THEY FAILED THE RESISTANCE CHECK LIMITS FOUND IN THE HS 748 MM. (TC NR 20071112003)