The Turbomeca Astazou is a highly successful series of turboprop and turboshaft engines, first run in 1957.

Fuel to the gas generator is adjusted automatically to maintain a constant propeller or rotor speed as blade pitch varies.

Power was steadily increased over the years, with the Eurocopter Dauphin's dual Astazou XVIII developing 783 kW each.

The Astazou XX received a third axial stage, raising compression even further to achieve a projected output of 1,075 kW (1,442 hp) in the turboprop application.

The XXB derivative, used in the single engine Aérospatiale SA 361H Dauphin, delivered 1,043 kW (1,399 shp).