As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ORD INFLIGHT T366/25JAN - REPORTED FUMES IN COCKPIT AND FLIGHT ATTENDANTS REPORTED BLUISH GREY SMOKE COMING OUT OF VENTS. HIGH TEMPERATURE PACK LIGHT ILLUMINATED. SMOKE SUBSIDED WHEN PACK TURNED OFF. RETURNED TO ORD AND LANDED WITHOUT INCIDENT. REPLACED RIGHT MOTOR PRIMARY AND SECONDARY HEAT EXCHANGER. ACCOMPLISHED PACK SYSTEM BURN OUT. SYSTEM GROUND CHECKED NORMAL OPERATION.