What was found
1:30 INTO FLIGHT RECEIVED LEVEL 1 FIRE DET 3 FAIL. REMOVED AND REPLACED #3 ENG FDCU, NO HELP ORIGINAL UNIT REINSTALLED. IAW AMM 26-11-02-4. TROIUBLESHOT PER MD11 FIM 26-11-00-2 AND WDM 71-51-11 FOUND LOWER TURBINE 'A' AND 'B' LOOPS RESISTANCE OUT OF LIMITS HIGH. FURTHER TROUBLESHOOTING FOUND BOTH 'A' AND 'B' LOWER TURBINE LOOPS BROKEN. R&R #3 ENG LWR FIRE DETECTOR LOOP ASSY, NEEDS OPS CHECK REF MD11 MM 26-11-03-4-1. ACCOMPLISHED TASK THROUGH STEP 3E(4). CONTINUE AT STEP 3E(5). FACT 04FEB22 22:29 IND U CONTINUED WITH R&R OF #3 ENGINE FIRE LOOP AT STEP 3.E.(5) TO COMPLETION PER MD-11 AMM 26-11-03-4-1 AND 26-11-02-5. OPS CHECK GOOD, NO FURTHER FAULTS NOTED.