What was found
FLT 2104, BOS-BOS. IMMEDIATALLY AFTER TAKE OFF, THE FLIGHT SMELLED ABNORMAL FUMES. CONTACTED DX MTC TO DISCUSS, MTC ADVISES TO SWITCH PACKS ON - OFF TO ISOLATE. DETERMINED IT WAS FROM PACK 2. AIR RETURN DUE TO ETOPS RESTRICTION, COMPLIED WITH INGO NOTICE 2017-T015L, PILOT DID NOT SUBMIT SMART SHEET. TREATED ODOR EVENT AS A CLASS 3 & PERFORMED LEVEL C DECON OF ECS SYSTEM W ENGINE BLEED. APU WAS USED FOR SECOND DECON. PER AMM 21-00-00-615-804-A OP TO SUBTASK 21-00-00-860132-C.), CONTINUED TO RUN BOTH PACKS AFTER REINSTALLATION OF DUCTING BETWEEN CONDESOR AND CHECK VALVE FOR PACK 1 AND 2 WITH APCU BLEED & ENG 2 BLEED PER AMM 21-00-00-615-804-A—NO ODOR PRESENT THROUGHOUT CABIN AND COCKPIT AT THIS TIME.