As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT#2260, MAD-BOS. (ETOPS) "ENG 1 FIRE LOOP A FAULT DURING PREFLIGHT ( ENGINE FIRE DETECTION SYSTEMS 1) LOOP A ); T/S PER TSM 26-12-00-810-803-A NO DEFECTS FOUND. FAUTL HAS NOT HIT IN FLIGHT PER PREVIOUS EGS + AVIATAR. AS PRECAUTIONARY REMOVED AND REPLACED FDU # 1 IAW AMM 26-12-34 OPS TEST GOOD MDDR CLEARED PALCARD REMOVED UPDATED MX-4.