What was found
AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED DUE TO: INFLIGHT HYDRAULIC-A QUANTITY DECREASED FROM 90% TO 57% IN 2 HOURS, LOSING 1% EVERY 4-MIN. AIRCRAFT DIVERTED TO AND LANDED SAFELY AT ORD. FOUND HYDRAULIC LEAK FROM NUMBER 1 ENGINE DRIVEN HYDRAULIC PUMP PORT PLUG ON PUMP BODY. TORQUED THE PLUG, PER AMM 20-50-11. RAN NUMBER 1 ENGINE IDLE FOR 5MIN. LEAK CHECK GOOD. HYDRAULIC QUANTITY WAS STEADY.