As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
HYD 3 LOW PRESSURE CAUTION MESSAGE DURING CRUISE. RAN QRH AND MESSAGE STAYED ON. MANUALLY EXTENDED GEAR. DIVERTED. DECLARED EMERGENCY. REPLACED O-RING SEALS ON HYD SYS NR 3 PRESSURE MANIFOLD ASSY IMPENDING BYPASS INDICATOR WITH SERVICEABLE UNITS IAW CMM. OPS AND LEAK CHECKS OK.