Abstract: A fastener assembly includes a washer element and a nut element. The nut element is split and includes a screw thread that threadably engages the thread of a bolt or other such fastener element to lock the nut to the bolt. The nut element is adapted by the split to assume an open configuration which permits the nut to move freely along the bolt without being threadably engaged with the bolt and a closed configuration which threadably engages the screw thread of the nut with the screw thread of the bolt. The washer is sized to move freely over the screw thread of the bolt, but to force the nut into the closed configuration when the washer and the nut are cooperatively engaged. The washer maintains the nut in threaded engagement with the bolt when the washer and the nut are cooperatively engaged on the bolt.