to torque or not to torque?

while working on my rudder i noticed that there is no mention of torquing the screws that hold the counterweight. Does one torque all bolts and screws on the plane? I tried to torque the screws to 100 inch pounds and couldn't stop the screwdriver fron slipping on the screw.!! I decided to stop and ask before proceeding further!!!!
btw, rv7
dennis

Torque

Refer to AC43.13.1b Chapter 7. It contains all the torque values for AC fasteners. The publication is Acceptable Methods, Techniques, and Practices should be very helpful.
T88
RV10

dennis said:

while working on my rudder i noticed that there is no mention of torquing the screws that hold the counterweight. Does one torque all bolts and screws on the plane? I tried to torque the screws to 100 inch pounds and couldn't stop the screwdriver fron slipping on the screw.!! I decided to stop and ask before proceeding further!!!!
btw, rv7
dennis

Click to expand...

I think you're confusing a AN509 with an AN5-sumthin. AN509 just refers to the style (100 degree head). So I think it's an AN509 10R24 bolt if I remember right. 10Rwhatever is a 10-32 screw, and the proper torque is 25in/lbs (same as an AN3-something). I can't ever remember how to decode the R24 part....has to do with the grip length, so I always have to look that up if I'm interested.

edit: I'll also mention that I'm a fraidy cat, so when I put mine in, I globbed a little epoxy w/microballoons on the bolts before I closed up the rudder. My thought is that those suckers are in there forever. YMMV...just how I did it

Torque Q

Hi,

I had the same Q previously that I asked Vans and their response was :-

" You don't Torque bolts unless they are going into something fixed like a nutplate - You torque the NUT and for those the correct setting is 20/25 inch pounds "

Happy building

Armstrong torque works well on anything AN4 and smaller.

Thanks for replys

thanks to all for the helpful information.
I looked up the section on fasteners and bolts, and now feel much better: torqued the nuts correctly this a.m. I appreciate this forum of builders where a non mechanical type can ask for help and stay out of trouble!
dennis, rv7 empennage: getting ready to order wings.

Just a quick comment on the "armstrong" method. Most folks will tighten stuff way too tight when using this method. 22 inch-pounds is only about a 3-4 pound pull on a typical wrench. If a guy's gonna torque things by feel, it might be a good idea to do a couple with a torque wrench first so as to gauge what "tight" feels like.

I torqued some AN-3's with my brand new, calibrated Mac torque wrench. I too was amazed at how the "correct" torque value seemed awfully loose. Couldn't stand it, so tightened em a fair amount more. The danger is if you go too far you can pretty easily pull the smaller bolts in half.

Another problem: you'll find there will be a lot of the smaller bolts in places where there's no way you're ever going to get a torque wrench on them. That's why it's important to develop a "feel".

I think (I hope) there's a fair bit of room between too loose and too tight torque on the small bolts. On the bigger ones, say the wing attach bolts, it's much more important to get close to the correct torque.

John Miller

osxuser said:

Armstrong torque works well on anything AN4 and smaller.

Click to expand...

Change that to "fingerstrong" and you're a bit closer to reality...

Look closely at just how small the threads are on an AN3-series bolt; it doesn't take a whole lot of over-torque to permanently deform those threads. As was said earlier, if you're not going to use a TQ wrench consistently on smaller hardware, it'd be a good idea to torque a couple same-size fasteners a couple times with the TQ wrench to get a feel for the correct torque.

When appling a specified torque to a nut/bolt combination always apply torque to the nut while holding the bolt stationary. Tightening or torqueing the bolt applies a twisting force to the bolt shank which would give a false torque reading. This method would apply to screws as well if they are installed in combination with a nut. Hold the screw/bolt, and tighten the nut. In actuality you are really s t r e t c h i n g the shank of the bolt or screw and if the shank has a twisting load and a tension load at the same time,.............well thats not good. False torque readings will also be indicated if using a socket extension, longer extension=larger error, due to the extension twisting when applying torque to the nut. Also, never apply thread lub as this will give a false or inaccurate torque reading.

Some call this "German" torque because it's "guttentite".

Jekyll