As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING PREFLT WITH APU RUNNING SMOKE FILLED THE CABIN. SHUTDOWN APU AND ELECTRICAL POWER. UPON INSP THE CABIN WEMACS WERE HOT. FOUND CRUSHED DUCT PN 6619016-68. REMOVED AND REPLACED WITH SERVICABLE. REPLACED ACM TURBINE. ALL OPS AND LEAK CHECKS GOOD. IAW MM 21-22-00.