What was found
PIT FLT1942 FLIGHT WAS HOLDING FOR LGA WHEN THE AIRCRAFT LOST THE A-SYSTEM HYDRAULICS. DUE TO ATC HOLDING AND LOW CEILINGS AROUND LGA, DECISION WAS MADE TO DIVERT TO A LONGER RUNWAY AND BETTER WEATHER. FLIGHT DIVERTED TO PIT AND LANDED WITHOUT FURTHER INCIDENT. AIRCRAFT WAS TOWED TO THE GATE. MAINTENANCE FOUND THE NR 1 ENGINE DRIVEN HYDRAULIC PUMP LEAKING TO THE CAVITY. REPLACED HYDRAULIC PUMP PER MM 29-15-12-4. ALSO, REPLACED A LEAKING O-RING ON PRESSURE FITTING TO HYDRAULIC FILTER MODULE. OPERATIONAL CHECK AND LEAK CHECK GOOD.