Date: 202012
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Flight conditions: Mixed
Weather elements / visibility: 5
Light: Night
Aircraft: B757-200
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Cargo / Freight / Delivery
Flight phase: Initial Climb
Airspace: Class B ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: Indicating and Warning - Hydraulics
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Second reporter function: Captain; Pilot Flying
Anomaly: Aircraft Equipment Problem Less Severe
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 Returned To Departure Airport; General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: The left yaw damper was deferred on the initial paperwork. Upon logbook review at the aircraft; the mechanic informed us the deferral was cleared which left us with no MELs. Pre-flight and taxi were uneventful. Shortly after takeoff with the Captain as PF; the L HYD QTY EICAS illuminated; followed by the L HYD ENG PUMP EICAS. As we were handed off to Departure on the ZZZZZ 5 SID; I saw the L HYD SYS PRESS; RUDDER RATIO; and YAW DAMPER EICAS messages momentarily appear; but they quickly extinguished without an associated Master Caution (that I can recall). The Captain elected to leave the Flaps at 5 and bugged the speed back accordingly. Departure cleared us to 10;000 ft.; but allowed us to stay at 5;000 ft. to run the QRH checklists. ATC provided vectors in the vicinity of ZZZ while we worked the problem. At the time the QRH was referenced; we had two EICAS messages displayed. The L HYD QTY checklist did not have any action items. The L HYD ENG PUMP checklist directed us to turn the engine pump OFF. Since I had momentarily seen the L HYD SYS PRESS message and the Status page indicated a loss of fluid in the left system (magenta RF); we referenced the L HYD SYS PRESS checklist; but did not perform any of the actions at that time since the EICAS was not illuminated. As we discussed a return to ZZZ; the L HYD SYS PRESS message reappeared; along with the YAW DAMPER and RUDDER RATIO messages; an associated Master Caution; and the SYS PRESS light on the overhead panel. We accomplished the QRH checklist up to the deferred items and advised ATC. The controller passed word of the priority handling to The Company at the Captain's request while we completed the DIVERT ACARS; got performance data with the L HYD SYS non-normal; and set up for an ILS to Runway XX. While on extended vectors; we tried extending the gear normally which resulted in a GEAR DISAGREE EICAS and POWER XFER UNIT Status message. In accordance with the deferred items on the L HYD SYS PRESS checklist; we accomplished the alternate gear extension procedures. Once turned back towards the airport; we attempted normal flap extension from 5 to 15. The TE FLAP DISAGREE message appeared; so we again followed the deferred items for alternate flap extension. I sent for performance data reflecting the new non-normal (L HYD SYS WITH TE FLAP DISAGREE) accounting for the Flaps 20 Vref 20 landing configuration. With the QRH complete; the Captain called for the applicable normal checklists and we briefed the approach with attention given to non-normals (manual speedbrake extension before right thrust reverser deployment; manual braking; etc) and how a go-around would be handled (gear would remain down; flap speeds; etc). Once handed off to Tower; we relayed that we would not have nose wheel steering. Our plan was to clear the runway onto a high speed taxiway to be towed; but if we couldn't stop by XX; we would probably have to shutdown on the runway for tow. Tower told us the runway was ours with CFR standing by and said they had notified Company of the need for tow. We had a jumpseater onboard that is another 757 First Officer. He had plugged a headset into the observer panel for assistance as needed and checklist backup. The Captain queried the crew as to if we thought everything was in order as we approached the FAF. We were in agreement that all checklists were complete and we felt comfortable with the approach and landing. The Captain landed; manually pulled the speed brake lever; deployed the right reverser; and conducted manual braking. He cleared [the runway] where we were met by CFR vehicles. After performing the After Landing flows (except leaving the flaps at 20); the engines were shutdown for CFR to inspect the aircraft/brakes. Once cleared by CFR; the priority handling was terminated and we were towed into Ramp by Company. There was not any visible hydraulic fluid on the aircraft exterior when maintenance first looked. We performed a Shutdown/Secure checklist; conducted aquick debrief with the mechanics to include the wording of the Captain's logbook write up; and left the aircraft with maintenance as we were directed to tail swap and continue to ZZZ1 under a new flight number. As the crew van arrived; hydraulic fluid was leaking onto the ramp from the left side of the aircraft while the mechanic continued to evaluate the problem. I still do not know what the root cause of the problem was and/or if there was anything that could have prevented the loss of fluid in the left hydraulic system. I feel our crew worked well together to safely recover the aircraft despite the backside of the clock showtime and it being our first leg flying together. ATC and CFR were very helpful throughout the event. I think our training prepared us for situations like this (heavy system hydraulic loss) and CRM principles were used to efficiently handle the issue to the best of our abilities at that time.


Second narrative: Shortly after takeoff (ZZZ) and passing approximately 1;000 ft. AGL; we heard a caution aural and saw L HYD QTY EICAS Msg. There was also an audible thump sound and slight feedback through the flight controls (yoke). This was followed quickly by L HYD ENG PUMP Msg. We were flying the SID (I was PF) and the aircraft was in LNAV and VNAV. I called for A/P CTR CMD; confirmed the A/P FMA and that the A/P was in fact functioning properly. Initially; we remained on the SID while analyzing our problem. A quick check of the status page confirmed that the left hydraulic reservoir had lost a significant amount of fluid (high of .98 to low of .21; .30 after shutdown). We also had a momentary L HYD SYS Press message that extinguished and came back on later (on downwind). Considering an air turn back likely; I decided to keep the flaps at 5. We requested a level off at our initial altitude of 5;000 ft. We let ATC know we had a hydraulic issue and that we desired vectors for a likely return to Runway XX at ZZZ. With the initial 'aviating; navigating and communicating' complete we agreed that L HYD QTY was; at that point; our first priority. After running this checklist the L HYD SYS PRESS light came on continuously leading to the running of that checklist. Having reached the deferred items section of the checklist we briefly discussed contacting dispatch. I decided that a return to ZZZ was clearly the safest and best option and that direct notification by us would be more of a distraction than help. I decided to advise ATC and request ATC notify 'company' of our hydraulic system issue. This and quick divert message sent via ACARS; satisfied the notification requirement. We had good weather; a long runway (at a very familiar field) and were well below max landing weight. Before beginning the configuration process we completed our normal procedures; including after takeoff and approach checklists; and set up & briefed the ILS for Runway XX. We began configuring and quickly discovered that the PTU was not operating properly; requiring the alternate extension procedures for flaps and landing gear. After requesting and receiving landing data for our non-normal configuration (per checklist); we requested a vector to intercept final. With the assistance of our jumpseater we reviewed all the pertinent notes and made sure we had considered all the pertinent variables; no autobrakes; manual speedbrake extension on landing; R thrust reverser; only after speed brakes extended and no nose wheel steering (differential braking only) on roll-out. We notified approach and Tower of need to have aircraft towed to parking either from runway or after clearing runway (high speed taxiway). I planned to use differential braking to exit the runway; but wasn't sure how effective this would be. As it turned out; aircraft control was more than adequate for exiting via the high speed exit taxiway. After taxiing clear of the runway we stopped the aircraft and coordinated a quick inspection of the aircraft by crash/rescue and a tug to tow us to parking.


Synopsis: B757 flight crew reported that a hydraulic system malfunction resulted in a diversion.