What was found
RT SYS PRESS EICAS ON DEPARTURE. UNABLE TO RESTORE SYSTEM PRESSURE VIA QRH. DECLARED EMERGENCY AND RTB TO CAN. EMERGENCY DECLARED. CONSULTED WITH FLIGHT CREW JUST R HYD SYS LIGHT ILLUMINATED AND R SYS PRESS EICAS, ELEC PUMP LOW PRESS LIGHT AND EDP LOW PRESS LIGHT NOT ILLUMINATED, R & R RT HYD SYS PRESSURE SWITCH S32 IAW AMM 29-11-17-4, ENG RUN CHECK ALL PARAMETERS NORMAL IAW JRH. PRECAUTIONARY R & R RT PRESS SENSE ENG HYD PUMP RELAY K127 IAW SWPM 20-81-22, WDM 29-31-11, & IPC 29-31-01-01A-060, PRECAUTIONARY R & R RT HYD PRESSURE TRANSMITTER M343 IAW AMM 29-31-01-4. PERFORMED HYD SYS OPS TEST IAW AMM 29-11-00-5, ALL 3 HYD SYS PRESSURE WERE STABLE AT 2800-3200 PSI, NO LEAKS FOUND.