Torquing bolt into Nutplate

[CharlieWaffles]

Van's says bolts should be torque into nutplates. But all of the torque guides are based on the NUT size in corrolation to a bolt. So for instance, in the diagram below, The AN3-5A bolts being inserted into the nutplates to secure the battery/bell crank mount, how should I determine the proper torque? Or even the AN515-8R8 bolts as well?

 

[flion]

First, the torque guides I know of are based on fastener/thread and then by application (shear/tension). I use the Standard Aircraft Maintenance Handbook, which lists the AN3 (10-32) as 20-25 in/lbs in tension. The AN515-8R8 fastener is an 8-32 screw but the guide works for screws as well: 12-15 in/lbs. Nutplates are rarely used in shear. You are out of luck when using fasteners smaller than 8-32 or non-structural fasteners unless you can get the manufacturer to guide you. A couple of good oddball resources are the GAHCo and Aircraft Spruce catalogs; they can at least help you identify what kind of fastener you are dealing with by the part number. And, of course, there is the ongoing debate about torquing; I suggest this thread:http://www.vansairforce.com/community/showthread.php?t=66472 Oh, wait, that's the thread you started a while back...

 

[jhearnsberger]

That's funny! I was on this section tonight too. I just snugged them up as best I could. I used a good bit of down pressure to keep my screwdriver from slipping.

 

[Wayne Gillispie]

Don't forget to add the drag torque.

I don't use a torque wrench on anything under #10. Go by feel. If there is alot of drag torque then more final torque will be needed.

Don't worry about installing that to specs, because you will have to remove it for elevator pushrod installation later on.