What was found
FLT 512, AUS - FLL. DIRTY SOCK SMELL WHEN USED APU BLEED, SMELL TRANSIENT & SUBSIDED AFTER CLIMBOUT, SMELL PRESENT BOTH COCKPIT & CABIN. UPON INITIAL INSPECTION, FOUND EVIDENCE OF AN EXTERNAL LEAK AT THE OIL COOLER LUBE LINES PROGRESSING DOWN TO THE LUBE MODULE & OIL TANK. FOUND EVIDENCE OF OIL IN INLET FLAPPER DOOR. CLEANED OIL FROM EXTERNAL SURFACES & RAN APU, NO LEAKS NOTED. ACCOMPLISHED INFO NOTICE 2017-T015F SECTION "B", ENGINES NOT AT FAULT. REPLACED RECIRCULATION FILTERS, PER M/M 21-21-41. R & R ORINGS ON OIL SUPPLY AND RETURN LINES, IAW AMM 49-21-00, LEAK CHECK GOOD. PERFORMED OPERATIONS CHECK OF APU, IAW AMM 49-00-00. OPERATIONS CHECK GOOD. MDDR CLEARED MX4 UPDATED PLACARD REMOVED.