G

gator

Active Member
Does anyone have any knowledge about the possibility of galling when using stainless steel screws in platenuts? What is the best way to prevent the screws from eventually seizing? I'm thinking about the screws for wingtips, inspection plates, landing lights, wheel pants, floorboards, etc.
 
To prevent this, use Neverseize, oil, tap out the nutplate. I personally have hundreds of #6 & 8 Torx flat head ss screws (floorboards, baggage, wing tips, inspection covers, fairings). I've only had 2 or 3 over the last 6-8 years and many hundreds of engagements gal. And these were abnormally tight installations. As a rule, I don't do anything special and rarely have problems.
 
Engineering Opinion

Typically, you'll have more of a problem when you have stainless attaching to stainless. That's much more prone to galling. When using dissimilar metals where one is softer than the other, you probably won't need to worry about it much.

And yes, using an anti-seizing compound (like Neverseez) will help...but gee freakin whiz that stuff makes a mess! A little bit goes a long, long way. I had a mechanic tell me one time that a plastic jar of that stuff can cover the entire state of Texas! :D
 
Boe-Lube

Try running a Boe-lube coated screw through every new nut plate after you install it. It makes them work great with cad-plated or stainless screws.

When I started playing with RV's, I learned to hate nut-plates - trying to put floor-board screws in to the -8 was frustrating as all get-out. then I discovered that if you use a little Boe-Lube on a screw the first time you put one in a nut-plate, it will be smooth (yet retain it's locking nature) forever. Boe-lube doesn't create the mess of anti-seize, and a single stick of the stuff should last through about a dozen RV builds.
 
bowl wax

2 buck toilet wax ring. Good for a billion screws. No mess, and works great.

Regards,
Chris
 
Lots of Good Suggestions

For many years in the fastener industry, a common finish has been cadmium and wax. The cad is put on as an electroplate, and the wax is nothing more than a dip and spin process using a diluted mixture of Johnson's floor wax. The purpose of the wax is for lubricity. Today, cadmium is virtually non-existent in the auto industry due to its carcinogenic nature. Interestingly, its still used in the aircraft industry due to superior corrosion resistance. The gold color typically seen on AC fasteners is a dichromate over the top of the cad.
Using stainless fasteners with all-metal locknuts (such as platenuts) is NEVER a good idea without at least some form of lubricity. Nylon lock nuts - no problem. In fact, you typically want to stay away from petro based lubes with nylon, as they may break down the polymer.
My suggestion for things where repeated removal is necessary - like seat pan fasteners, inspection covers, and wingtips is to tap out the nutplate. While some users suggest running a fastener in and out to soften or season the lock, it really has pretty much the same effect - repeated use of a lock nut (typically more than 5 or 6 times) typically destroys the locking mechanism. In fact, the existing SAE specifications for locking fasteners typically spells out first on, first off, and fifth off prevailing torque as a means of qualifying the product. There is no spec after the fifth use. In any event, I've tapped out all of the above listed fasteners in my plane. After over 500 hours, no problems with loosening in any of these locations.
Terry, CFI
RV-9A N323TP
 
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