As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW - CREW REPORTED LEFT HAND PACK FAILED IN FLIGHT. EMERGENCY DECLARED FLIGHT RETURNED DFW LANDED WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. FOUND HOSE BETWEEN PACK PRECOOLER AND LOW LIMIT VALVE LOOSE. RE SECURED HOSE. SYSTEM GROUND CHECK NORMAL OPERATION.