What was found
AFTER TAKEOFF, CREW NOTICED A LOW HYDRAULIC PRESSURE INDICATION WHEN THE LANDING GEAR WAS RETRACTED. LATER IN THE CLIMB THERE WAS AN INDICATION FOR LOSS OF HYDRAULIC PRESSURE FROM THE NR 1 ENGINE DRIVEN PUMP. THE CREW ELECTED TO RETURN TO BASE FOR MAINTENANCE DUE TO THE UNAVAILABILITY OF REPLACEMENT PARTS AT THEIR DESTINATION. THE AIRCRAFT RETURNED AND LANDED WITHOUT INCIDENT. MAINTENANCE REPLACED THE NR 1 ENGINE DRIVEN HYDRAULIC PUMP. AFTER SUCCESSFUL LEAK AND PRESSURE CHECKS, THE AIRCRAFT WAS RETURNED TO SERVICE.