AN AIRCRAFT

An aircraft comprises a machine body. The machine body encloses a turbofan gas turbine engine. The turbofan gas turbine engine comprises, in axial flow sequence, a heat exchanger module, a fan assembly, a compressor module, a turbine module, and an exhaust module. The heat exchanger module is in fluid communication with the fan assembly by an inlet duct. The heat exchanger module comprises a plurality of first heat transfer elements, with the first heat transfer elements being configured for the transfer of heat energy from a first fluid contained within the first heat transfer elements to an airflow passing over a surface of the first heat transfer elements prior to entry of the airflow into an inlet to the fan assembly. The first fluid contained within the first heat transfer elements has a temperature TF, and the airflow passing over the surface of the first heat transfer elements has a temperature TA. The turbofan gas turbine engine further comprises at least one second heat transfer element, with the or each second heat transfer element being configured for the transfer of heat energy from the first fluid to a second fluid.In use, the aircraft can maintain a sustained airspeed V (M), and when the airflow temperature TA is less than the first fluid temperature TF, the first fluid passes through the first heat transfer elements. When the airflow temperature TA is equal to or greater than the first fluid temperature TF, the first fluid passes through the second heat transfer elements.