As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT#2104, BOS-LGW. (ETOPS) 'ON APPROACH TO LANDING ENGINE 2 FIRE LOOP A FAULT APPEARED ON ECAM. ( ENGINE FIRE DETECTION SYSTEMS 1) LOOP A ); REMOVED AND REPLACED FDU 2 PER AMM 26-12-34 PB401. THE OPS CHECK IS GOOD. NO FAULTS NOTED. THIS CLEARS MDDR 490121. INOP PLACARD REMOVED. MX-4 UPDATED. MCC NOTIFIED.' (SUPPLEMENTAL INFORMATION ADDED TO DESCRIPTION)