Nutplates - Installing the Stall Warning Switch

OK, this just doesn't look correct to me.

I'm on page 16-02 installing the stall warning switch.



When I'm putting the screws AN525-8R8's into the nutplates, I feel like I re-tapping the nutplate. The screw comes out the back side looking like that's what I'm doing.



Of course the head of the screw is taking a beating as well and will need to be replaced.



I've double checked to make sure the K1000-08 nutplates installed on the rib and it appears that I have the correct screw specified in the plans.

This can't be correct. What am I missing?

Thanks,

Bob

I found that not ALL nutplates are good nutplates. Somehow they get squished too much or something. Try running the right screw into a spare nutplate. I actually twisted the threads off an AN3 bolt and it made for a real nightmare.
I also found that a drop of boelube will do wonders for a tight one as well.
As for the phillips slot, I am so happy I found the diamond and laser phillips bits by Wera, worth every penny they cost!

Bolts and screws hold by tension on the threads, not friction on the threads. Boelube helps but if you get a bad nutplate, run the correct tap through it. I recommend you do that on, at least, every removable access panel nutplate. You will thank yourself at the first annual. It is a real nightmare when you strip a screw - which will always happen in a very tight, limited access place - I learned that on a Bonanza. EAA has a video on doing that, it is a somewhat controversial practice and you can find the opposite opinion.

Having learned from helping a friend build an RV-9A, some nutplates are way too tight for sure. Am now in the habit of running a stainless screw through each one lubed with Boelube prior to install to verify the nutplate is not so tight as to destroy the threads as one batch was doing on my friends RV-9A. I made a small jig by drilling holes in a piece of wood and used mandrels from pop rivets pounded into the wood to hold the nutplates secure while running the screws into the nut plates.

I?m building E-AB and could see the potential for a colossal hassle if the stall warning switch?s Philips mounting screws were to get stripped in such a limited access area. I substituted those with aircraft grade Allan head cap screws and happy to have done so. If you are building E-LSA guess you will have to wait until after your phase one flight testing for such a change in hardware.

The Boelube worked great!

I can see where hex head screws would be the way to go there. It would be a major pain to try and do it after the pink slip. Hopefully, I'll be close enough in my adjustment that it won't take much more.

Thanks,

Bob

Mmmm,,,

It did not look like an AN525 to me

I've run a tap thru nut plates and I have used a dab of grease, but I always ask myself what are the stresses and consequences of failure. Low stress and consequence opens a lot of options. High stress and especially high consequence of failure definitely makes me take a closer look.

GAHco said:

It did not look like an AN525 to me

Click to expand...

What should it look like? As far as I can tell this was the part, but I've been wrong before...

Its easier to catch now rather than later...

Bob

AN515

In the first post the drawing shows to use an AN515. I believe the screw shown is correct.

There was a typo in the post that said AN525. This would be a washer head screw - much larger head. No need, and probably wouldn't fit, in this application. AN515 is correct.