What was found
PIT - FLT 1107 - EN ROUTE FROM YYZ TO CLT, AT FL350, THE CABIN ALTITUDE ALERT SOUNDED AS CABIN WAS AT 10,000 FEET AND CLIMBING AT APPROXIMATELY 600 FEET PER MINUTES. CREW INITIATED DESCENT TO FL115 AND COMPLIED WITH QUICK REFERENCE HANDBOOK PROCEDURES BUT OUTFLOW VALVE WAS NOT CONTROLLABLE. FLIGHT DIVERTED TO PIT AND LANDED WITHOUT FURTHER INCIDENT. NO OXYGEN MASKS WERE DEPLOYED AN NO EMERGENCY WAS DECLARED. MAINTENANCE ACCOMPLISHED OPERATIONAL CHECK PER MM 21-31-00 AND FOUND THE AFT OUTFLOW VALVE INTERMITTENT. REMOVED AND REPLACED AFT OUTFLOW VALVE. OPERATIONAL CHECK GOOD. (M)