An aircraft comprising: one or more engines; an auxiliary power unit; and a hydraulic system comprising: a first hydraulic subsystem including a first hydraulic pump and a first set of hydraulic-powered components (112, 114, 116) in fluid communication with the first hydraulic pump, the first hydraulic pump powered by the engine to pump shared hydraulic fluid to the first set of hydraulic-powered components (112, 114, 116); a second hydraulic subsystem including a second hydraulic pump and a second set of hydraulic-powered components (126, 128, 130) in fluid communication with the second hydraulic pump, the second hydraulic pump powered by the auxiliary power unit to pump the shared hydraulic fluid to the second set of hydraulic-powered components (126, 128, 130); a shared return line subsystem in fluid communication with the first and second hydraulic subsystems (102, 104) to return the shared hydraulic fluid from the first and second sets of hydraulic-powered components (112, 114, 116, 126, 128, 130) to the first and second hydraulic pumps (106, 120); and wherein the first hydraulic subsystem is a flight essential hydraulic subsystem which includes only hydraulic-powered components (112, 114, 116) that are essential during flight and the second hydraulic subsystem is a non-flight essential hydraulic subsystem which includes only hydraulic-powered components (126, 128, 130) that are not essential during flight, but are instead used during ground operations and pre-flight checks. one or more engines; an auxiliary power unit; and a hydraulic system comprising: a first hydraulic subsystem including a first hydraulic pump and a first set of hydraulic-powered components (112, 114, 116) in fluid communication with the first hydraulic pump, the first hydraulic pump powered by the engine to pump shared hydraulic fluid to the first set of hydraulic-powered components (112, 114, 116); a second hydraulic subsystem including a second hydraulic pump and a second set of hydraulic-powered components (126, 128, 130) in fluid communication with the second hydraulic pump, the second hydraulic pump powered by the auxiliary power unit to pump the shared hydraulic fluid to the second set of hydraulic-powered components (126, 128, 130); a shared return line subsystem in fluid communication with the first and second hydraulic subsystems (102, 104) to return the shared hydraulic fluid from the first and second sets of hydraulic-powered components (112, 114, 116, 126, 128, 130) to the first and second hydraulic pumps (106, 120); and wherein the first hydraulic subsystem is a flight essential hydraulic subsystem which includes only hydraulic-powered components (112, 114, 116) that are essential during flight and the second hydraulic subsystem is a non-flight essential hydraulic subsystem which includes only hydraulic-powered components (126, 128, 130) that are not essential during flight, but are instead used during ground operations and pre-flight checks. a first hydraulic subsystem including a first hydraulic pump and a first set of hydraulic-powered components (112, 114, 116) in fluid communication with the first hydraulic pump, the first hydraulic pump powered by the engine to pump shared hydraulic fluid to the first set of hydraulic-powered components (112, 114, 116); a second hydraulic subsystem including a second hydraulic pump and a second set of hydraulic-powered components (126, 128, 130) in fluid communication with the second hydraulic pump, the second hydraulic pump powered by the auxiliary power unit to pump the shared hydraulic fluid to the second set of hydraulic-powered components (126, 128, 130); a shared return line subsystem in fluid communication with the first and second hydraulic subsystems (102, 104) to return the shared hydraulic fluid from the first and second sets of hydraulic-powered components (112, 114, 116, 126, 128, 130) to the first and second hydraulic pumps (106, 120); and wherein the first hydraulic subsystem is a flight essential hydraulic subsystem which includes only hydraulic-powered components (112, 114, 116) that are essential during flight and the second hydraulic subsystem is a non-flight essential hydraulic subsystem which includes only hydraulic-powered components (126, 128, 130) that are not essential during flight, but are instead used during ground operations and pre-flight checks.