What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Aileron torque tube TIP

Mel

Mel

Legacy Member
Mentor
I have inspected quite a few RV-10s now, and find one consistent problem. The forward and aft ends of the aileron torque tube at the wing root aren't long enough to end up with one complete thread showing when built according plans. Since these nuts aren't carrying any load, they may be replaced with the thinner AN-364 "shear nuts".
I have talked with Ken Krueger at Van's, and he agrees with my solution. They will make changes to the plans.
 
Still the case?

Mel -

I am now building my aileron torque tubes (RV-10) and happened to read your old post on this yesterday, then mounted the tubes last night. It was obvious what you were referring to, but I haven't seen any plans revision or service bulletins from Van's on the topic. Do you still recommend using the thinner nuts, essentially deferring to good "nut technique" over the plans callouts? I'm a new builder.
 
Bryan,

I don't know the answer, but out of curiosity, how old is your wing kit?

Phil
 
douglassmt said:
Mel -

I am now building my aileron torque tubes (RV-10) and happened to read your old post on this yesterday, then mounted the tubes last night. It was obvious what you were referring to, but I haven't seen any plans revision or service bulletins from Van's on the topic. Do you still recommend using the thinner nuts, essentially deferring to good "nut technique" over the plans callouts? I'm a new builder.
Click to expand...
Yes, the technique is acceptable. The "thin" nuts are called "shear nuts" because they are not designed to carry "tension" loads. In this case, the nuts don't carry any tension loads.
 
Thanks

Thanks. I'll order some AN364-428 nuts. Same torque as the nuts called out in the plans, I assume.
 
Negative!

douglassmt said:
Thanks. I'll order some AN364-428 nuts. Same torque as the nuts called out in the plans, I assume.
Click to expand...
The torque value for shear nuts is less than for tension nuts. Typically the value for shear nuts is about 60% of tension nuts.
 
It's not knowing the stuff. It just knowing where to find it.
And of course, dealing with it every day helps too.
 
Mel,
I've got to admit I'm a little puzzled by the logic here.

In this case, it seems like one is reducing the amount of contact between threads in exchange for an ability to verify that the part is not coming loose because we can see the thread is still showing. Is this correct?

At the same time, it would seem that reducing the thread contact (thinner nut) would increase the likelihood of a contact loosening.

Thanks,
Tom Hanaway
 
tomhanaway said:
Mel,
I've got to admit I'm a little puzzled by the logic here.

In this case, it seems like one is reducing the amount of contact between threads in exchange for an ability to verify that the part is not coming loose because we can see the thread is still showing. Is this correct?

At the same time, it would seem that reducing the thread contact (thinner nut) would increase the likelihood of a contact loosening.

Thanks,
Tom Hanaway
Click to expand...
On the contrary. We are assuring that the "nylon" locking device is being used in it's entirety. Thread contact for the nut itself is not as important in a "shear" application.
 
nuts

As I was tooling along making those tubes I had a sort of brain spin and instead of drilling the tube per the dimensions given, I welded the bolts to the ends of each tube. I inserted the 2 haves in the wing root between the bearings and slid them apart to make a snug fit between bearings. I marked them at this point, took them out and then drilled the locking bolts. I think this made my tubes a splash longer than the plans but I had a perfect fit and I do have one thread showing but it sure is a skinny thread. I noticed this after I was finished and it sure dawned on me that was a close call. If I had made them by the dimension they would have been a tiny bit shorter with a little slop between bearings..
 
I just received my wing kit yesterday and the correction to the AN365-428 nut was made in my plans.

Steven Stella
#40654 Wings
N521RV reserved
 
Another short one

I installed the tube that goes from the bellcrank to the aileron tonight and noticed that the AN3-7 bolt making the connection to the tube at the bellcrank also is too short for the nut to torque with 1-2 threads showing - seriously short. However, I've also noticed some variation in bolt length among my bolts. I have one of those fancy gauges that tells you bolt length and the AN3-7 bolts I have from Van's register slightly over the length for AN3-6 bolts - nowhere near the length listed for AN3-7s. So... I will probably order another batch of AN3-7 bolts and see if they are longer. There isn't an AN3-8 bolt so if those don't work I'll have to look at the thin nut again. I could also use an L washer I suppose, but I don't think that will get me the thread length I need. Any change in the recent plans for that nut also? Your thoughts, Mel?
 
douglassmt said:
There isn't an AN3-8 bolt so if those don't work I'll have to look at the thin nut again. I could also use an L washer I suppose, but I don't think that will get me the thread length I need. Any change in the recent plans for that nut also? Your thoughts, Mel?
Click to expand...

Not sure what bolt you're talking about. I'll have to take a look at the plans. A thin washer is an acceptable method of getting proper threads showing if that works.
BTW an AN3-8 would actually be an AN3-10. (1" and no 1/8ths)
 
douglassmt said:
I installed the tube that goes from the bell-crank to the aileron tonight and noticed that the AN3-7 bolt making the connection to the tube at the bell-crank also is too short for the nut to torque with 1-2 threads showing - seriously short. However, I've also noticed some variation in bolt length among my bolts. I have one of those fancy gauges that tells you bolt length and the AN3-7 bolts I have from Van's register slightly over the length for AN3-6 bolts - nowhere near the length listed for AN3-7s. Your thoughts, Mel?
Click to expand...
These bolts are obviously AN3-6 bolts. Acquire AN3-7 bolts and use the proper bolt length.
 
Bolts, nuts, nutplates

I'm running up against some situations I don't know the answer to on bolt and nut technique. For instance, some bolt/nut combos you can meet two of the three criteria: keep no more than one thread inside the work, keep 1-2 threads showing above the nut when torqued, and keep the grip at the end of the work or covered by not more than three washers - but not all three. In other words, if I have to, should I leave more threads showing above the torqued nut in order to keep no more than 1 thread inside the work and the grip at or inside the work/washers?

Another question: do the same rules apply to screws and bolts in nutplates?

And: Do you torque screws the same as bolts, whether in nutplates or nuts?

And: Do you torque bolts in nutplates the same as in nuts?

Don't mean to obsess, but I gather that this issue is important and I want to get it right.
 
Bolts come in length sizes by 1/8". Washers (up to 3 allowed) are either 1/16" (std) or 1/32" (L). There should be no reason that you can't use a combination to meet all three requirements.
 
To answer the other questions (off the top of my head; you really should read the AC on this...): Generally you do not put a washer between a nutplate and what it is fastening. If a bolt is too long, the washer(s) go under the bolt head. Typically, the shank should be just long enough to go through the work, leaving only threads to go into the nutplate. No need to worry about number of threads showing if you follow the above. Screws typically have their own torque values depending on thread, material, and design. I'd have to look to be sure but I think the torque values do differ if you are using a nutplate. Different material and all...

Edit: Ok, I'm still not positive on all of this. My house copy of AC 43.13 dates from 1988. Structural screws (those with an unthreaded shank) torque the same as bolts and are included in the table of torque values. Non-structural screws have no table given. Nutplates are not mentioned at all.
 
Last edited:
You must log in or register to reply here.
Back
Top