Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 242; Flight Crew Total 5242; Flight Crew Type 5242
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Clearance
Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport
Aircraft
I was Captain of Flight XXX; ZZZ-ZZZ1. Normal takeoff and climb to FL340. At XA40Z the #2 engine driven hydraulic pump low pressure light illuminated. Hydraulic pressure system B slowly dropped to a very low indication with the system B pressure showing 2;980 PSI. The QRH (Quick Reference Handbook) was ran. Dispatch was contacted via frequency and a patch with Maintenance Control was initiated. B system quantity was showing 106 with pressure holding around 3;000 PSI. It was decided that the indicator failed and we (Dispatch; Maintenance Control; and Flight Crew) decided that it was fine to continue to ZZZ1. The FO (First Officer) and I decided to closely monitor the hydraulic systems as we continued. Approximately 6 to 8 minutes later; we saw the B system pressure drop to 100 psi with a zero quantity indicated. We ran the Hydraulic System B failure checklist in the QRH; contacted Dispatch and Maintenance Control. We decided to return to ZZZ. We requested priority handling and returned to ZZZ with an uneventful landing on RWY XXL per the QRH.
B737 flight crew reported hydraulic failure in cruise resulting in a return to departure airport.