Abstract: The present invention relates to propeller blades which are mounted in a rotatable propeller hub and pivotable in the same by means of inner shafts with axes substantially radial to the axis of rotation of the hub and countersunk in said hub and located inside an outer peripheral edge of the same. The propeller hub is positioned in an shroud means, a tunnel or similar with a surrounding wall, which is substantially circular and concentric to the axis of rotation of the hub. The propeller blade has a blade vane with an outer edge with portions shaped as peripheral arcs concentric to the hub axis and having a play to the surrounding wall which is smaller than the necessary radial movement which is required for the lifting of said shaft over the peripheral edge of the hub when the propeller blade has to be demounted from the hub.