What was found
PDIS 789 29-02 4718 05OCT21 MEM OPEN U DURING CRUISE THE C HYD ELEC 2 EICAS MESSAGE APPEARED FOLLOWED BY A COMPLETE REDUCTION OF C HYDRAULIC QUANTITY. SHORTLY AFTER THE FOLLOWING EICAS MESSAGES APPEARED: C HYD SYS PRESS C HYD RSVR PRES C HYD QTY R YAW DAMPER DECLARED AN EMERGENCY, COMPLETED THE QRH PROCEDURES, AND LANDED THE AIRPLANE SAFELY WITHOUT ANY OTHER ISSUES. FACT 06OCT21 07:10 MEM INSTALLED NEW ACMP REF. AMM 29-11-02-4. OPS CHECKS GOOD. NO LEAKS NOTED. REMOVED & REPLACED CENTER SYSTEM ACMP PRESSURE & CASE DRAIN FILTERS 4EA. REF. AMM 29-11-19-4. NO LEAKS NOTED. PERFORMED YAW DAMPER SYSTEM TEST REF. AMM 22-11- 00-5. AIRCRAFT OK FOR SERVICE.