Aircraft fuelling

A method of operating a gas turbine engine, the gas turbine engine comprising:

• a combustor, comprising an annular combustion chamber and a plurality of fuel spray nozzles configured to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor is operable in a condition in which the first subset of fuel spray nozzles are supplied with more fuel than the second subset of fuel spray nozzles, wherein a ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:2 to 1:5;
• one or more fuel-oil heat exchangers;
• and
• a plurality of ignitors;
• the method comprising:
• providing a fuel to the one or more fuel-oil heat exchangers;
• transferring heat from oil to the fuel in the one or more fuel-oil heat exchangers;
• and
• providing the fuel from the one or more fuel-oil heat exchangers to the plurality of fuel spray nozzles;
• wherein
• heat is transferred from the oil to the fuel in the one or more fuel-oil heat exchangers to raise a temperature of the fuel to an average of between 135° C. and 200° C. on injection of the fuel into the combustion chamber at cruise conditions,
• the plurality of fuel spray nozzles are arranged circumferentially spaced around the combustor within a liner of the annular combustion chamber and positioned at a same radial distance from a rotational axis of the gas turbine engine, and
• the plurality of fuel spray nozzles are controlled differently such that the first subset of fuel spray nozzles are supplied with more fuel than the second subset of fuel spray nozzles below a staging point,
• wherein two of the fuel spray nozzles of the first subset are positioned opposing each other on opposite sides of the combustor,
• wherein each of the first subset of fuel spray nozzles is located nearer a respective one or more of the ignitors than the second subset, and
• wherein one or more of the ignitors is arranged diametrically opposite another one or more of the ignitors.