322 fig3 b shows spring 334 in a relaxed or uncompressed state in which it resists rotation of the shaft of blade 304 in different embodiments of the invention spring 334 may be compressed or tensioned when blade 304 is transitioned from its failure position to its operating position but its equilibrium state substantially corresponds to the failure position of blade 304 thereby biasing the blade toward that position illustratively the length of slot 324 may correspond to the degree of rotation needed to rotate blade 304 between its operating and failed positions thus in fig3 a b if blade 304 rotated approximately forty five degrees then slot 324 may extend approximately forty five degrees about the circumference of bore 322 in one alternative embodiment of the invention slot 324 may be aligned substantially perpendicular to the axis of bore 322 in this alternative embodiment blade 304 would not be extended from hub 306 when it rotates into its operating position from its failure position instead as the hub spins faster the force of air upon the open blade may overcome the bias of spring 334 and cause the blade to rotate into its operating position when the hub slows sufficiently the bias of spring 334 would cause the blade to rotate back into its failure position one of ordinary skill in the art would recognized from the preceding description how the embodiment of the invention depicted in fig3 a b could be modified for an apparatus in which the airfoils are to fail into a u201c closed u201d position fig4 7 demonstrate other means for biasing a blade or airfoil toward a failure position according to alternative embodiments of the invention in fig4 blade 410 is.