Anchor Nut: Definition and Installation Instruction

Anchor nuts are captive nuts that do not require an ordinary hex nut to tighten an aircraft bolt. They are used when it is nearly impossible to work on the backside of a piece you are bolting. When certain part installation makes hex nut usage unattainable, anchor nuts are the go-to alternative to bolting a piece together from one side only. It is not unusual for a typical all-metal homebuilt aircraft to have more than two to three hundred anchor nuts installed to reach assembly completion.

Anchor nuts can be the only way to make some installations. Frequently affected problem locations are inspection access covers and hatches, cowling attachments, installation of accessories on the firewall, the installation of antennas, propeller spinner/bulkhead installation, the attachment of wing root fairings, and instrument panel installations. Installations that require the use of anchor nuts are called “blind installations” because the opposite side for installing and torquing ordinary nuts is inaccessible.

The two most commonly used anchor nut varieties include the two lug nylon insert locking type and the two lugs all-metal anchor nut. Other less frequently used anchor nuts are the all-metal floating anchor nut, the one lug nut, corner nuts, and even miniature nuts for limited space installations. In the tightest of spots, when the standard two lug anchor nut or even the miniature anchor nut will not fit, use of the corner nut and the one lug anchor nut are your best alternatives.

Basic procedure for installing the 832 anchor nut (the most popular size and easiest to install) is a 5 step process.

  • Clamp assembly and drill ?” pilot holes for aircraft fasteners.
  • Separate assembly.  Aircraft clamps anchor nuts to structure and drill rivet holes.
  • Remove anchor nuts and countersink/dimple rivet holes.
  • Install anchor nuts. Insert rivets and set with a rivet squeezer or rivet gun.
  • Carefully drill fastener holes to size

At Paragon Purchasing, owned and operated by ASAP Semiconductor, we can help you find the anchor nuts you need, new or obsolete. As a premier supplier of parts for the aerospace, civil aviation, and defense industries, we're always available and ready to help you find all the parts and equipment you need, 24/7x365. For a quick and competitive quote, email us at or call us at +1-714-705-4780.


March 21, 2022

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