At the beginning of this work, the discoveries and innovations in the historical development of gas turbines that preceded the development of today’s modern aircraft engines are described. The importance of turbo-fan engines for the development of air passenger transport and their improvements and difficulties during development is stated. A technical description of the GEnX engine is made, explaining its working principles. The main parts of the engine and their many improvements and advantages are described. A thermodynamic analysis of the engine is carried out in which the Brayton cycle is described, the characteristic points of the process are calculated and specific works of the fan, low- and high-pressure compressors and turbines are obtained. Based on the obtained data, excess air, specific fuel consumption and the efficiency of the process are calculated. An assembly drawing of the GEnX-1B-70 engine with its main parts and an auxiliary systems schematics was made.