As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CMH - FLT 407 - ON CLIMB, CREW REPORTED THE NR 1 ENGINE BLEED WENT TO 90 PSI AND THE LEFT PACK SHUT DOWN. DUE TO APU BEING INOPERATIVE, CREW RETURNED TO CMH AND LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE REMOVED AND REPLACED THE PRESSURE REGULATOR. LEAK AND OPERATIONAL CHECK NORMAL. AIRCRAFT RELEASED FOR FURTHER SERVICE. (M)