As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ORD - FLT 430 - EN ROUTE ORD-DCA AT 16,000 FEET, PACK ONE ILLUMINATED ON MFDU. SHORTLY AFTER COCKPIT FILLED WITH SMOKE. TURNED PACK NR 1 OFF AND ACCOMPLISHED SMOKE/FIRE PROCEDURES CHECKLIST. RETURNED ORD AND LANDED WITHOUT FURTHER INCIDENT. REPLACED FLOW CONTROL VALVE. SYSTEM GROUND CHECKED NORMAL OPERATION. (M)