Gas turbine performance

A gas turbine engine for an aircraft, the gas turbine engine comprising:

• a combustor arranged to combust a fuel;
• a fuel management system arranged to provide the fuel to the combustor, wherein the fuel management system comprises:
• two fuel-oil heat exchangers arranged to have oil and the fuel flow therethrough, the two fuel-oil heat exchangers arranged to transfer heat between the oil and the fuel and comprising a primary fuel-oil heat exchanger and a secondary fuel-oil heat exchanger;
• and
• a fuel pump arranged to deliver the fuel to the combustor, wherein the fuel pump is located between the two fuel-oil heat exchangers;
• and
• a controller that is configured to control the fuel management system so as to transfer between 200 and 600 KJ/m3 of heat to the fuel from the oil in the primary fuel-oil heat exchanger at cruise conditions,
• wherein a ratio of heat transfer from the oil to the fuel for the primary fuel-oil heat exchanger and the secondary fuel-oil heat exchanger is between 70:30 and 90:10 at cruise conditions, and
• wherein relative to a flow path of the oil starting at an oil tank, the secondary fuel-oil heat exchanger is upstream of the primary fuel-oil heat exchanger.