Definition
A self-locking nut permanently attached to an aircraft structure or component, used to receive a screw or bolt from the opposite side. Anchor nuts are typically riveted in place so the fastener can be installed or removed from one side only, without needing to hold a nut on the back.
Plain English
A nut that is fixed in place on the aircraft so a screw can be threaded into it from the other side. You don't have to reach behind the panel with a wrench because the nut is already held there.
Context Anchor
Seen in aircraft maintenance, especially where removable panels, covers, or interior parts are attached to the aircraft.
Derivation
Called an 'anchor' nut because it is anchored — held firmly in place — to the structure. The word 'anchor' comes from the Latin 'ancora,' meaning a device that holds something in a fixed position. The name captures the key idea: the nut doesn't move or spin when the screw is turned.
Why Pilots Care
Allows reliable, one-sided fastening in confined spaces while resisting vibration and maintaining structural integrity.
Intuition Check
An anchor nut is not used to anchor the aircraft to the ground. It is a nut anchored to the aircraft structure so a screw or bolt has something fixed to tighten into.
Example Sentence 1
After removing the inspection panel, the mechanic noticed one of the anchor nuts had cracked and needed to be replaced before the panel could be reinstalled.
Example Sentence 2
Anchor nuts along the wing spar let the technician install bolts without a helper on the opposite side.