A heat management system for an aircraft powered by a gas turbine engine, the heat management system comprising: (a) a fuel tank storing a fuel; (b) a first heat exchanger thermally coupled to the fuel tank; (c) a hydraulic pump for circulating a hydraulic fluid for hydraulically actuating one or more hydraulic components of the aircraft; (d) a hydraulic circuit comprising: a first hydraulic line fluidly coupled to the first heat exchanger and the hydraulic pump, wherein the hydraulic pump receives the hydraulic fluid from the first heat exchanger via the first hydraulic line; and a second hydraulic line fluidly coupled to the first heat exchanger and the hydraulic pump, wherein the hydraulic pump supplies the hydraulic fluid to the first heat exchanger via the second hydraulic line, such that the first heat exchanger brings the hydraulic fluid and the fuel into a heat exchange relationship; (e) an oil circuit for circulating an oil to lubricate one or more components of the gas turbine engine requiring lubrication; and (f) a second heat exchanger thermally coupled to the oil circuit and at least one of the first hydraulic line and the second hydraulic line, such that the second heat exchanger brings the hydraulic fluid and the oil into a heat exchange relationship, thereby allowing heat transfer between the fuel and the oil via the hydraulic fluid; characterised in that the heat management system has a fuel line fluidly coupled to the fuel tank; a fuel-oil heat exchanger (FOHE) fluidly coupled to the fuel line and the oil circuit, such that the FOHE brings the fuel and the oil into a heat exchange relationship; a low pressure fuel pump configured to supply the fuel from the fuel tank to the FOHE via the fuel line; and a high pressure fuel pump configured to receive the fuel from the FOHE and supply the fuel to an engine line that is in fluid communication with one or more burners of the gas turbine engine. (a) a fuel tank storing a fuel; (b) a first heat exchanger thermally coupled to the fuel tank; (c) a hydraulic pump for circulating a hydraulic fluid for hydraulically actuating one or more hydraulic components of the aircraft; (d) a hydraulic circuit comprising: a first hydraulic line fluidly coupled to the first heat exchanger and the hydraulic pump, wherein the hydraulic pump receives the hydraulic fluid from the first heat exchanger via the first hydraulic line; and a second hydraulic line fluidly coupled to the first heat exchanger and the hydraulic pump, wherein the hydraulic pump supplies the hydraulic fluid to the first heat exchanger via the second hydraulic line, such that the first heat exchanger brings the hydraulic fluid and the fuel into a heat exchange relationship; a first hydraulic line fluidly coupled to the first heat exchanger and the hydraulic pump, wherein the hydraulic pump receives the hydraulic fluid from the first heat exchanger via the first hydraulic line; and a second hydraulic line fluidly coupled to the first heat exchanger and the hydraulic pump, wherein the hydraulic pump supplies the hydraulic fluid to the first heat exchanger via the second hydraulic line, such that the first heat exchanger brings the hydraulic fluid and the fuel into a heat exchange relationship; (e) an oil circuit for circulating an oil to lubricate one or more components of the gas turbine engine requiring lubrication; and (f) a second heat exchanger thermally coupled to the oil circuit and at least one of the first hydraulic line and the second hydraulic line, such that the second heat exchanger brings the hydraulic fluid and the oil into a heat exchange relationship, thereby allowing heat transfer between the fuel and the oil via the hydraulic fluid; characterised in that the heat management system has a fuel line fluidly coupled to the fuel tank; a fuel-oil heat exchanger (FOHE) fluidly coupled to the fuel line and the oil circuit, such that the FOHE brings the fuel and the oil into a heat exchange relationship; a low pressure fuel pump configured to supply the fuel from the fuel tank to the FOHE via the fuel line; and a high pressure fuel pump configured to receive the fuel from the FOHE and supply the fuel to an engine line that is in fluid communication with one or more burners of the gas turbine engine.