A turboprop1 is a type of gas turbine engine that drives a propeller. Compared to a turbojet, the exhaust gases barely contain any energy to produce significant thrust. Instead, they are used to move a turbine connected to a shaft. Approximately 90% of the thrust is produced by the propeller and the remaining 10% by the exhaust gases.2 The turboprop is an intermediate point between the reciprocating engine and the turbojet. Its optimal operating conditions are between 400 and 640 km / h and between 5400 and 9000 m. Its specific minimum fuel consumption is at an altitude between 7,600 m and tropopause.3 It generally requires about two thirds of the fuel used by a turbojet per passenger.4 For this reason, they are mainly used in small and medium subsonic aircraft, although some larger aircraft such as the Airbus A400M are also equipped with turboprops.