Abstract: Stall elimination means in a jet turbofan engine includes a plurality of pairs of generally parallel case struts arranged in an annular row in an annular fan bypass duct of the engine, and a series of freely-rotatable vanes, each vane disposed between a pair of the struts and movable between open and closed positions. In its open position, each vane is aligned with the direction of normal, positive air flow in the duct, while in its closed position it extends generally across the duct and blocks most reverse air flow in the duct. The vane automatically rotates to the closed position in response to the onset of an adverse pressure gradient in the duct.