Nutplate Tip

I recently read a forum comment from someone who had a lot of trouble with nutplates, and actually broke off a screw in one because it was so tight. My experience so far with the empennage and wing kits has taught me a couple of lessons that I will share in hopes of saving someone else a lot of grief.

Because they are so tight, and invite screw head stripping and worse, I have adopted the practice of testing all nutplates before installation. I put them in my vise (before countersinking the mounting holes) and manually drive the matching screw or bolt into the nutplate, using a bit of the Boelube dry lubricant on the threads. This gets the first insertion out of the way in a controlled environment before installation in the airframe, making subsequent insertions easier, and also will identify any defective unit or buggered up threads.

Sure is a lot easier doing this on the bench, instead of in some hard to reach place on the assembly.

It's also important the hole is properly sized and aligned with the nutplate or you will cross thread the bolt in the nutplate. When the bolt is first inserted, it should turn easily then the resistance will increase. If resistance is immediate, stop and back out to determine the cause or just try again. John's tip will help reduce the resistance when properly engaged, but across threaded bolt will just get tighter.
Another tip is when riveting nutplates, a hardware bolt with an O-ring under the head can be inserted in the bolt hole along with a cleco in one rivet hole. Once a rivet is placed in the opposite end, the bolt can be removed to allow room for the rivet squeezer. The O-ring simply prevents scratching from the bolt head. When squeezing the rivets, especially countersunk type, be sure the rivet set does not contact the center of the nutplate as damage will occur. Don't ask me how I know. Another excuse to buy new parts. Avery Tools sells a small diameter rivet set that is ideal for this situation.

I guess we all have our Vices!

I guess we all have our Vices!
But.....

I do not use mine to test nutplates.

I drop my nutplates (one at a time) on my 90 degree Snap-Ring Pliers with the 3/32 prongs.

No Crush, stays were you put it and quick to use.

I tighten the friction nut once the nut plate is on and then loosen it when I am done with testing the batch.

PS. I only test them if they are going in a critical and difficult place to remove.

Just lube the screws

I also had an issue with easily stipping the head of the screws when putting them into nutplates early in my build. One day I saw someones suggestion on VAF to lube with boelube before the first install and have had no problems since. Don't waste time checking them, they are all made to spec and how do you know the screw tolerance may not be the reason for rejecting one. Install nutplates, lube the screws and go on.

Season them

I made a cool little jig that holds the nutplate. Then I drive a hex head screw in with a cordless drive and back out. Done deal. You can do about 2-3 a minute.

Doing this you "season" the nutplate and confirm the integrity of the threads. I installed a couple of nutplates that had bad threads. Of course, they were in a difficult location. No problems now.

FYI, I've got a guy that is going to manufacture these for me.

If I have a nut plate that gives me grief I put a matching tap in a battery drill, lube it up, and use it to clean out the threads in the nut plate. Works every time.

Lubing is probably better than tapping.

I have tapped the threads in nutplates also, but with care and thought about where that nutplate is located. The fit of the screw in the nutplate is tight for a reason, so think about it before cleaning it up with a tap. If it matters if the screw would come out, I suggest you tap it tap it by hand so you can feel it when the tap starts to cut and maybe only go half a turn then try a screw to make sure it still grips the screw.

I had one nutplate that was so tight I messed up the screw slots with the screwdriver trying to remove it & had to use vice grips on the head to remove it. That one got tapped.

No bueno Amigo!

Tapping a nutplate does alter its properties.

I would suspect the fastener is out of spec, or the screwdriver bit is worn.

A little lube or exercising of the nutplate with a hex screw like the earlier lister stated.

The NAS1096 or NAS1801 screws are great for this, they are hard enough to flexersize the oval part of the nutplate without galling the threads of either the screw or the nutplate.

The stronger alloy the screws the more consistent the locking system will work. The softer screws the more likely they are going to stick and gall.

stripped screw heads

I seem to recall someone mentioned using a very small amount of automotive polishing compound on the screwdriver tip to improve "traction" and reduce likelyhood of striping cross-tip (Phillips) screw heads.

Also, I've stopped using cheap screwdrivers. They're made of soft metal and have tapered vanes (if that's what they're called). I bought a half dozen driver tips from Snap-On that are holding up well and they also have some small ribs in the "vanes" to help hold on. Haven't stripped a screw head in a while.

I have problems with nutplates on occation. What I do is run the drill bit size for the screw to make sure that there isn't any overlap of the skin to the nutplate, just touch it a bit. If there still is a problem, I'll run a tap, either 6-32 or 8-32 for the normal screw nutplates and only go in one or two threads, if the nutplate has a problem it's generally the start. I've never had any problems with nutplates using this method.

Nutplates

For years, Skybolt purchased and sold all variations of Nylon insert and All-Metal locking nutplates. The Nylon insert parts became very pricey and are hit or miss on availablity. Then the strange non-availabilty of standard all-metal nutplates in 2007-2008. Along with this experience, we converted an industry clip-on nutplate from non-locking to locking. We discovered the extreme difficulty in setting a consistant locking torque. Thus, the all-metal platenuts, although cheap, tend to eat up screws, but worse, break screws (thanks China). The old style MS21078 versions work much better and are gentle on screws.

We looked at industry pricing on nylon insert platenuts and found a large customer willing to pay the costs associated with producing this design in quantity. Skybolt just completed a Skytanium version of MS21078-3 platenuts, black anodized. These parts meet the axial pull-out ratings of steel, at 60% weight savings! They are now available in standard 3/32 rivet (-3) and 1/8 rivet (-38). Please refere to our website www.skybolt.com (Purchasing) for part numbers and pricing or contact Aircraft Spruce or General Aviation Hardware.

They are not cheap (it is a machined part), but they do answer the problem associated with the parts that are cheap.

Have a safe SunNFun...we will be on the flight line daily....

Regards,

Ned Bowers