As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED ODOR IN THE CABIN AFTER TAKEOFF, RETURNED TO FIELD AT MKE AND HAD EMERGENCY EQUIPMENT DISPATCHED. A/C LANDED WITHOUT INCIDENT AT MKE. MAINTENANCE WAS DISPATCHED TO THE A/C AND REPORTED THE NR 2 PACK SYSTEM WAS THE CAUSE, AND PLACED IT ON MEL 21-51-00-1. THE A/C WAS THEN RETURNED TO SERVICE.