What was found
ACFT DEPARTED ABOUT 30 MIN INTO FLIGHT, CREW OBSERVEDE AN EICAS MESSAGE "HYD PRESSURE LOW LT". CREW CHECKED ALL READINGS AND NO ABNORMAL PRESSURE OR VOLUME INDICATIONS NOTED. UNLOADED RIGHT ENGINE HYD SYS AND NOTED SYS PRESSURE TO DROP TO 500 PSI. VOLUME INDICATION WAS NORMAL. FLIGHT CREW ATTEMPTED DEPLOYING SPOILERS WITH LT SYS LT ONLINE BUT NO SPOILER DEPLOYMENT INDICATION WAS NOTED ON PILOTS MFD. CREW THEN FLEW REMAINDER OF THE TRIP WITH RT SIDE HYD SYS ENABLED. MX WAS DISPATCHED AND TROUBLESHOT DISCREPANCY TO A BAD LT HAND HYD MANIFOLD. OPEN