What should be done if a fiber or nylon insert-type, self-locking nut can be threaded on a bolt with only fingers?

If a fiber or nylon insert-type, self-locking nut can be threaded onto a bolt with just fingers, it indicates that the locking mechanism is compromised. The function of the fiber or nylon insert is to create friction and provide resistance to loosening due to vibrations. If the nut can be installed easily without tools, this suggests that either the insert is damaged or worn out, reducing its ability to lock effectively.

Using such a nut could lead to critical failures, as it may not properly secure the connection during operation, potentially jeopardizing safety. Therefore, the appropriate action is to reject the nut to ensure that only reliable and secure fasteners are used in assembly. It's vital to maintain the integrity of components in any assembly process to prevent accidents or failures.