As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT FAILED TO PRESSURIZE AFTER TAKEOFF. FLIGHT RETURNED TO MEM AND LANDED WITHOUT INCIDENT. MAINTENANCE FOUND LOOSE INSULATION BLANKET STUCK IN OUTFLOW VALVE. REMOVED INSULATION. OPERATIONAL CHECK NORMAL. AIRCRAFT RETURNED TO SERVICE.