What was found
ALL THREE F/A REPORTED DIRTY SOCKS SMALL AFT PORTION OF AIRPLANE AND TOP OF DESCENT UNTIL LANDING. DUE TO CABIN ODORS IFE SYS CONSIDERED INOP. DUE TO CABIN ODORS POSSIBLE CAUSE ENG NR 2 BLEED SYS CONSIDERED INOP. GROUNDED - YES. PERFORMED T/S TO IDENTIFY CABIN ODORS IAW TSM 05-50-00-810-831-A & TBN 4430-04. POSSIBLE CAUSE NR 2 ENG BLEED SYSTEM. VERIFIED CABIN ODOR OCCURS ON APU BLEED DUE TO LUBE MODULE LEAKING. R&R APU LUBE MODULE PER AMM 49-91-45. OPS/LEAK CK GOOD. CLEANED APU AREA AND PERFORMED PRE-CONDITIONING WITH APU BLEED PER AMM 12-33-21. NO FOUL SMELL NOTED.