A feathering device for the fan blades of a turboprop engine that includes at least one set of fan blades with adjustable orientation is provided. The assembly is attached in rotation to a rotating cowling connected to a turbine rotor. Each blade is coupled, for the adjustment of its orientation, to a control ring that is movable between two extreme positions, one of which corresponds to feathering of the blades. Mechanical parts are able to extend elastically as a result of a rise in their temperature, these mechanical parts being positioned facing the control ring so as to be able to exert a thrust force on the ring in order to put it in a position to feather the blades when they expand. A device to cause a rise in the temperature of the mechanical parts so as to expand them is also provided.