As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TAXI OUT, FLT ATT REPORTED REAR OF AIRPLANE FILLING RAPIDLY WITH SMOKE. A/C EVACUATED VIA DOOR SLIDES, OVERWING EXIT DOORS AND REAR STAIRS. POSSIBLE RT PACK MALFUNCTION. REPLACING ALL FOUR DOOR SLIDES, CHECKED AND REINSTALLED OVERWING EXIT DOORS. T/S RT PACK SYSTEM, FOUND FLOW MULTIPLIER TRIPPING APU BLEED. REPLACED FLOW MULTIPLIER.