As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AIR RETURNED AND DECLARED AN EMERGENCY. SMOKE IN THE CABIN. FOUND RIGHT PACK AIR CYCLE MACHINE SEIZED CAUSING SMOKE. DEFERRED IAW MEL 21-42A, RT PACK INOPERATIVE. MAINTENANCE REMOVED AND REPLACED RT ACM IAW AMM 21-52-02. OPS CHECK GOOD.