As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
10 MINUTES AFTER SECURING LEFT PACK IAW BLEED TRIP, QRH PROCEDURE, CABIN ALTITUDE WARNING SOUNDED. EMERGENCY DECLARED, DONNED THEIR OXYGEN MASKS AND DIVERTED FLIGHT, LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE REPLACED 450 SENSOR PER AMM 36-11-05 AND REPLACED PRECOOLER CONTROL VALVE IAW AMM 36-12-02 AND PERFORMED SATISFACTORY OPERATIONAL CHECK IAW AMM 71-00-00-00.