What was found
DISCREPANCY: REFERENCE LP1159041-1 AIR-TURN-BACK. FUME EVENT REPORTED BY FLIGHT ATTENDANTS. FOLLOWED ELIMINATION OF ODOR CHECKLIST, ISOLATED PACK 1, NO IMPROVEMENT. ISOLATED PACK 2 SHOWED ODOR DISSIPATION. CORRECTIVE ACTION: AIRCRAFT WAS GROUNDED DUE TO DISCREPANCY. MAINTENANCE PERFORMED TROUBLESHOOTING PER TSM 05-50-00-810-831-A. DETERMINED SOURCE OF ODOR BY DECISION TABLE TO BE PACK #2, DEACTIVATED PACK #2 AND PLACED ON MEL 21-52-01H. CONTROL # 1144316 DUE DATE 11/11/2018, MX PROCEDURE COMPLIED WITH.