B777-200
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 200.3; Flight Crew Total 11828.83; Flight Crew Type 1479.38
Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Fuel Issue
Flight Crew Landed As Precaution; Flight Crew Returned To Departure Airport; General Maintenance Action
Aircraft
Shortly after takeoff; we received an alert for low pressure in the left hydraulic system; HYD PR L. A review of the system schematic indicated a complete loss of hydraulic fluid in that system. We delegated responsibilities and pulled up the corresponding applicable checklist. ATC was notified as the problem warranted a return to [departure airport]. The checklist was completed and we were instructed by ATC to hold at [an] intersection. Dispatch and [Maintenance] were notified and agreed with our return decision as this was an ETOPS flight over extensive open ocean. We declared the need to dump fuel to ATC and requested a proper place to do so. We were cleared by ATC to dump fuel at 10;000 feet. We informed the flight attendants during the entire process. The passengers were kept informed as well. The diversion guide was followed and we dumped fuel so as to land below maximum landing weight. We evaluated landing performance data relative to our hydraulic problem and determined we were safe to land based on performance criteria and factors of the degraded condition. We also consulted Dispatch and obtained landing data from them. We completed all applicable checklists and landed uneventfully and returned to the gate.
B777 First Officer reported returning to departure airport following the loss of pressure and fluid in the left hydraulic system.