As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DEPARTING THE CREW OBSERVED THAT THE ARCRAFT WAS FAILING TO PRESSURIZE NORMALLY. THE AIRCRAFT RETURNED TO POINT OF DEPARTURE AND LANDED WITHOUT FURTHER DIFFICULTY. MAINTENANCE REPLACED THE NR 1 BLEED AIR SHUTOFF VALVE AND THE AIRCRAFT WAS RETURNED TO SERVICE. (TC NR 20070507012)