As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE, THE RT HYD PRESSURE WAS AT ZERO AND THE LT HYD WAS FLUCTUATING. THE CREW RETURNED TO DEPARTURE WITHOUT FURTHER INCIDENT. MX FOUND RESERVOIR DEPRESSURIZTION VALVE LEAKING. REPLACED RESERVOIR DEPRESSURIZATION VALVE. OPS CHECK GOOD IAW UAL MM29-13-35, UAL MM 29-13-43 PAGE 202 AND ERH 29.06.01-3 APPENDIX "A". ACFT WAS RETURNED TO SERVICE.