What was found
TWENTY MINUTES INTO THE FLIGHT, THE CREW RECEIVED A CAS MESSAGE STATING THE EMERGENCY PARKING BRAKE ACCUMULATOR PRESSURE WAS LOW. THE CREW FOLLOWED THE QUICK REFERENCE HANDBOOK AND TURNED ON THE STAND BY PUMP TO MANUAL AND SET THE PARKING BRAKE FOR 10 SECONDS. THE LIGHT WENT OUT. AFTER ANOTHER TWENTY MINUTES THE CREW RECEIVED THE SAME INDICATION AND FLIGHT 4063 RETURNED TO PIT. MAINTENANCE INSPECTED AND REPLACED THE HYDRUALIC CHECK VALVE IN ACCORDANCE WITH DORNIER MAINTENANCE MANUAL 29-00-00. OPERATIONAL CHECKS WERE PERFORMED AND THE AIRCRAFT WAS RELEASED FOR SERVICE.