Abstract: A locking fastener utilizing an inserted key preferably includes a fastener and a lock key. The fastener includes a drive head and a threaded shank. The drive head is preferably a countersunk head. A drive cavity is formed in a top of the drive head. The threaded shank extends from a bottom of the drive head. The lock key preferably includes a tapered head and a shank. The shank extends downward from a bottom of the tapered head. A head projection extends outward from a rear of the tapered head. At least one shank projection extends outward from a front of the shank. A key slot is formed in a side of the drive head and a side of the threaded shank. A head retention slot is formed in the key slot, adjacent a top of the drive head to receive the head tapered projection.

Abstract: A key for locking a threaded insert in a carrier material is provided with an improved tang portion. The improved tang portion includes spring retention means for reducing the friction required to position and hold the key within an insert slot prior to final installation and provide superior driveability over known prior art keys. The spring retention means includes a flexure area and a pair of protrusions which are held by spring force against the walls of the insert slot. The flexure area is centrally located on the tang portion and includes an aperture therein.