As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON PREFLIGHT, FIRE DETECTION TEST, THE NR 1 ENGINE A LOOP WOULD NOT SELF TEST. ACFT GROUNDED. VERIFIED DEFECT, FOUND ENGINE CORE DETECTOR A LOOP TERMINAL BROKEN. TERMINATED THE A LOOP TERMINAL IAW AMM 26-11-02, OPS TEST PASSED IAW AMM 26-11-00.