The Turbomeca Astazou is a highly successful series of turboprop and turboshaft engines, first run in 1957. The original version weighed 110 kg (243 lb) and developed 240 kW (320 shp) at 40,000 rpm. It was admitted for aviation service on May 29, 1961, after a 150-hour test run. The main developing engineer was G. Sporer. It was named after two summits of the Pyrenees.
A simplified version was built by Agusta as the Turbomeca-Agusta TA.230.
The Astazou IIA version was derived from the original Astazou powerplant for use in helicopters. By 1993, 2,200 had been built. As of 2007, it was still in production. However, many aircraft initially equipped with it, especially the heavier ones, have since been upgraded with more powerful engines.
The early single-shaft Astazou has a two-stage compressor, with the first stage an axial and the second stage a radial design. It has an annular combustion chamber, after which the combustion gases enter a three-stage axial turbine.
Engines have a reduction gearbox in front of the air inlet, with an output speed suitable for a propeller or, for helicopters, as the first stage only of the much bigger reduction required for a rotor. Fuel to the gas generator is adjusted automatically to maintain a constant propeller or rotor speed as blade pitch varies.
Handley Page HP.137 Jetstream, with twin Astazou XIV, showing the distinctive annular air inlet and long reduction gear housing
As of the Astazou X, the engine received a second axial compressor stage. This was the engine for the Potez 840. The Astazou XIV and XVI were also marketed by Rolls-Royce Turboméca International Ltd under the names AZ14 and AZ16, respectively.
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).
