Date: 202103
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: Marginal
Weather elements / visibility: Wind
Light: Night
Aircraft: B757-200
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Cargo / Freight / Delivery
Flight phase: Descent
Airspace: Class C ZZZ
ATC / advisory: TRACON ZZZ1
Aircraft component: Hydraulic System Pump
Component problem: Failed
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Second reporter function: First Officer; Pilot Flying
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Landed in Emergency Condition; Flight Crew Overcame Equipment Problem; Flight Crew Requested ATC Assistance / Clarification; General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Descending on the STAR arrival around 11;000 ft. the FO (First Officer) deployed spoilers to slow and as the handle was moved we received a EICAS message for Hyd system pressure 'L'; hyd quantity; spoilers; rudder ratio etc. We selected hydraulic synopsis and noted left quantity '0' and pressure was low. As the fluid depleted the PTU engaged and L hyd pressure came up to 2800-3000 psi. We asked for an extended downwind for Runway XX and referenced the QRH HYD SYSTEM PRESSURE (L ONLY). We leveled at 6;000 ft. heading southwest. Slowed to 210 kts. and the FO continued flying as I accomplished the required items. After checking landing distance we decided to request Runway XY in case of steering issues or fluid leakage to not shut down Runway XX. We [advised ATC] asking for men and equipment standing by even though pressure was adequate. In the event any other systems were compromised. We configured to Flaps 1 normal. Continued to configure and slow and lowered the landing gear on an extended 15 mile final so we would have time to deal with any other issues that may arise. I took the controls as pilot flying and briefed the FO on various options we had in case of missed approach or control issues on the ground. FO did a tremendous job monitoring and capturing errors as they arose like finalizing checklists and call outs. We landed normal and stopped on Runway XY; cleared the runway at XX and stopped for crash rescue inspection of left wing area. We were informed fluid was leaking aft of number 1 L engine and shut down the L engine. We started the APU and shutdown R engine. We were informed brake temps were less than 150 and no smoke or fumes present. I referenced the various checklists regarding fluid loss and was told the leak had slowed. We coordinated with ZZZ operations; maintenance and ground control when fire rescue requested a clean up for hydraulic fluid on taxiway. Then maintenance tugged us back to the ramp at Gate XX. Failure of hydraulic component during descent while deploying speed brakes/flight spoilers. But I missed the fact at first that the loss of pressure on checklist has various systems and at first I referenced the pressure loss of L and C and then realized it was just the L quantity and pressure we were dealing with.


Second narrative: I was the Pilot Flying; on descent through 11;000 ft. I deployed the flight spoilers. Shortly after; we had a master caution 'L HYD SYS PRESS' along with associated messages and lights on the hyd system panel on the overhead panel. The CA (Captain) checked the status page; when I looked at the status page L hyd quantity was at or near 0; and the pressure was normal (near 3000). There appeared to be a hydraulic leak with the PTU operable. I continued flying; we asked for vectors for an extended approach. The CA ran the checklist and [advised ATC]. We ran the HYD SYSTEM PRESSURE left only found on QRH 13.1.5. The checklist refers to a situation where the PTU is inoperable or complete loss of hydraulic fluid. We considered either one of these situations conceivable; so we opted for extended vectors and early configuration in case we needed alternate extension on either the flaps or the landing gear. We also elected to land on Runway XY so we wouldn't shut down Runway XX in case nose wheel steering was unavailable. The CA took the aircraft for the approach and landing. We configured and landed using flaps 20 per the checklist and cleared the runway uneventfully. Upon clearing; the fire trucks met us and informed us that we were leaking hydraulic fluid out of our left side. We turned on the APU and shut down both engines and the leak stopped. Maintenance towed us to our gate uneventfully.[Cause was a] Failed O Ring on left hydraulic system equipment.


Synopsis: B757 flight crew reported that a hydraulic system failure resulted in a precautionary landing.