What was found
SMOKE IN CARGO BAY - MAIN CARGO DECK; NO SMOKE OR FIRE INDICATIONS; RAN SMOKE REMOVAL CHECKLIST DURING RETURN; OCCURRED ON CLIMBOUT ABOUT 15000' MSL. ISOLATED APU AND NR 3 ENGINE BLEEDS AND DETERMINED THE NR 3 ENGINE BLEED SYS INOPERATIVE. R & R ALL COALESCER BAGS AND PERFORMED DUCT BURN. REACTIVATED NR 3 PACK IN REF TO MEL DMP 21-51-1-0-1. PERFORMED OPS CHECK OF NR 3 PACK IN REF TO MM 21-53-20-5. PACK OPS CHECKED NORMAL.