What was found
DURING CLIMB, AT 4200MSL, THE CREW HEARD A NOISE AND DETERMINED THERE WAS A PROBLEM WITH THE PRESSURIZATION SYSTEM. THE CREW CONTACTED MAINTENANCE CONTROL AND WENT THROUGH TROUBLESHOOTING STEPS FOR A SOLUTION BUT THE PROBLEM PERSISTED. THE CREW WAS INSTRUCTED TO RETURN TO PIT. ON THE RETURN TO PIT THE MANUAL MODE BEGAN TO PRESSURIZE THE CABIN QUICKLY. FLIGHT 4066 LANDED WITH NO FURTHER INCIDENTS. MAINTENANCE INSPECTED AND REPLACED THE PRESSURIZATION CONTROL PANEL IN ACCORDANCE WITH DORNIER MAINTENANCE MANUAL 21-00-00. OPERATIONAL CHECKS WERE PERFORMED AND THE AIRCRAFT WAS RELEASED FOR SERVICE.