As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR TURNBACK AT APPROXIMATELY FL 220, SMOKE IN AFT CABIN ALONG WITH BURNING ODOR THROUGHOUT CABIN. SLIGHT ODOR IN COCKPIT 10 MIN LATER. PACK 2 FAIL FOLLOWED BY BLEED 2 FAIL APPEARED. PERFORMED SMOKE/ABNORMAL ODOR IN CABIN/COCKPIT CHECK IAW TSM 21-20-00-810-801A. FOUND NR 2 ACM TO BE AT FAULT MEL APPLIED.