As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RETURNED TO FIELD DUE TO SMOKE IN CABIN. ACARS MANAGEMENT UNIT WAS REPLACED DUE TO A POPPING ACARS MU CIRCUIT BREAKER ALONG WITH SMOKE PRESENT IN CABIN. SHOP CONFIRMED THE REMOVED ACARS MANAGEMENT UNIT HAD A FAILURE OF THE A6 POWER SUPPLY BOARD AND RESULTED IN THE PART BEING SCRAPPED.