A turbo machine airfoil, such as a blade or a vane in a compressor, in which the airfoil root portion includes screw threads having a dove tail cross sectional shape, and the rotor disk includes holes having similar screw threads such that a blade or vane can be easily replaced by unscrewing the old blade or vane and screwing in a new blade or vane. A locking pin biased by a spring is located in the root of the airfoil to lock the airfoil in the threaded hole to prevent the airfoil from loosening due to vibrations and to lock the airfoil in place at a desired angle of attack for maximum efficiency of the turbo machine. The removable cover plate is located on the casing and over the rotor disk such that the blade can be removed through the opening without the need to disassemble the turbo machine.