As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CREW REPORTED A ENGINE NR 1 FIRE DETECT FAIL ON TAKEOFF. MAINTENANCE INSPECTED AND PERFORMED STEPS OF FIM 26-11-00-810-803A INCLUDING ALL ELECTRICAL STEPS LISTED. NO FAULTS FOUND. REPLACED THE NR 1 DATA ACQUISITION UNIT. OPERATIONAL CHECKS WERE GOOD.