What was found
THE A-HYDRAULIC SYSTEM QUANTITY AND PRESSURE BEGAN TO DROP WHILE CLIMBING THROUGH 24,000 FEET EN ROUTE FROM MDW TO EWR. THE LOSS WAS ACCOMPANIED BY ILLUMINATION OF THE A-HYDRAULIC SYSTEM WARNING LIGHT. A MANUAL GEAR EXTENSION WAS REQUIRED. THE AIRCRAFT WAS DIVERTED TO CLE WHERE IT LANDED WITHOUT INCIDENT. MAINTENANCE FOUND THE NR 1 ENGINE HYDRAULIC PUMP LEAKING. THE HYDRAULIC PUMP WAS REMOVED AND REPLACED PER OP NR 1 OF EA 2910-01325, REV D. OPERATIONAL AND LEAK CHECKS WERE GOOD.