TWENTY‐FIVE years ago, the gas turbine was successfully applied to aircraft propulsion for the first time and it was not long after this event that powerful engines of reasonable efficiency appeared. In strong contrast with the early success of large engines, the evolution of equally efficient small engines has proved both difficult and protracted. That few of the major manufacturers have persisted with their development may be surprising but is also indicative of the technical problems involved. Thus it reflects great credit upon Turboméca that they have produced the first turbines to offer a serious challenge to piston engines for small aircraft installations. In this connection, the Astazou occupies a significant position as the first small propeller turbine to achieve any real measure of success, and it has been developed progressively to maintain its early lead over competitors. Consequently this engine was the obvious choice to power the Turbo‐Skyvan.