What was found
CREW REPORTED HYD 1 LOW PRESSURE CAS MESSAGE IN FLIGHT EN ROUTE FROM CAK TO PHL. CREW DIVERTED TO PIT AND LANDED WITHOUT INCIDENT. MAINTENANCE INSPECTED AND TIGHTENED A LOOSE B-NUT ON NUMBER ONE HYDRAULIC SYSTEM PRESSURE MANIFOLD INLET LINE. MAINTENANCE ALSO REMOVED AND REPLACED NUMBER ONE EDP (ENGINE DRIVEN PUMP) BECAUSE OF DRY OPERATION DUE TO THE HYDRAULIC FLUID LOSS AND PERFORMED CHECKS. ALL WORK ACCOMPLISHED BY MAINTENANCE USING AIRCRAFT MAINTENANCE MANUALS. AIRCRAFT RELEASED FOR SERVICE.