Airplanes feature a variety of fasteners. In addition to traditional fasteners like bolts, washers and nuts, many of them feature alternative fasteners like nutplates. Also known as anchor nuts, nutplates are stationary nuts that are riveted in place. You can use nutplates to secure threaded fasteners.

All nutplates feature a threaded hole in the center. After riveting a nutplate in place, you can twist a threaded fastener into this hole. When shopping for nutplates, though, you may discover that some of them are fixed and others are floating.

What Are Fixed Nutplates?

Fixed nutplates are characterized by a completely rigid construction that doesn’t move. Like their floating counterparts, they have a center hole to support a threaded fastener, and most fixed nutplates feature two other holes to support a pair of rivets. Fixed nutplates are simply “fixed” in the sense that the center hole doesn’t move once installed.

What Are Floating Nutplates?

Floating nutplates, on the other hand, feature a moveable hole. The two holes for the rivets are typically stationary, but the center hole is moveable. And with a moveable center hole, floating nutplates offer increased tolerances than fixed nutplates.

Differences Between Fixed and Floating Nutplates

Nutplates can be classified as either fixed or floating depending on whether the center hole is able to move after installation. You can install both types of nutplates by riveting them in place. Rivets are permanent fasteners. They are commonly used in the aerospace manufacturing industry because of their resistance to vibrations. While vibrations may loosen other types of fasteners, this isn’t a concern with rivets. Regardless, both fixed and floating nutplates are riveted in place.

Only floating nutplates, though, have a moveable center hole. The center hole — the hole that supports a bolt — can move around. After riveting a floating nut in place, you’ll have a twist a bolt into the center hole. If the nutplate isn’t properly aligned with the bolt, you may struggle to insert it into the center hole. Floating nutplates offer a solution.

You don’t have to align floating nutplates with bolts — at least not precisely. Even if a floating nutplate is just slightly off, you can insert the bolt into the center hole. This is because the center hole is moveable. All floating nutplates have a moveable center hole. You can move the center hole so that it becomes aligned with the bolt. Fixed nutplates have a fixed center hole, whereas floating nutplates have a moveable center hole.