What was found
DURING CRUISE, HYD 1 LO QTY EICAS MSG. QAUNTITY WAS 16%, AFTER LANDING QAUNTITY WAS 2% , BUT CAME UP TO 4% AFTER PARKING. REMOVED FROM SERVICE. INSPECTED AND FOUND HYD FLUID ALL AROUND INSIDE OF #1 HYD PUMP AND RESIVOUR AREA, SERVICED #1 HYDRAULIC SYSTEM TO 40% INSPECTED AND FOUND HYD SYS #1 TO BE LEAKING FROM ACMP PRESSURE ATTENUATOR. REMOVED AND REPLACED HYD SYS #1 ATTENUATOR O-RING. REF E175 AMM 29-11-29-000/400-801-A. OPS TEST GOOD WITH NO LEAKS NOTED. RETURNED TO SERVICE.