As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SMOKE APPEARED IN CABIN, PACKS WERE TURNED OFF. FIRST OFFICER NOTICED FLUID DRAINING THROUGH APU DRAIN VENTS, THEN APU AUTO SHUT DOWN. FOUND OIL LEAKING FROM APU. FOUND APU OIL CASE CRACKED. REMOVED AND REPLACED APU IAW CRJ MM 49-10-00. ALL OPS AND LEAK CHECKS GOOD. P/N ON: 3800488-3 S/N ON: P279C P/N OFF: 3800488-2 S/N OFF: P615