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Torque on nuts on aileron hinges

nohoflyer

Well Known Member
Patron
First I want to say I realize most AN-3 bolts get torqued to 20-25 inch pounds. Having said that, I feel that torquing down the bolts/nuts on the hinges will impede smooth movement of the control surface. This question also goes for the bolts on the bell crank.

Any thoughts?
 
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You should torque them down. The bolt clamps down on the center sleeve of the bearing and the rest of the bearing rotates around that immobile sleeve. nothing should be rotating on the bolt.

Edit: Forgot to mention- the 20-25 inch pound number doesn't include the friction of a locking fastener. if you're torquing a fiber lock nut you need to bump that number up by the value of the friction resistance of the nut. You can put a bolt in a vise and measure the torque it takes to crank a nut onto it, then add that to the base figure. An AN3 isn't much, so I typically just shoot for 25-28ish and call it good.
 
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If you torque the nuts and the ailerons don’t move freely, something is wrong with the alignment of the rod end bearing-center bearing, or the washers and bushings in the center.

This has been described in detail on VAF a while ago.

Getting this right can be very challenging. I got very good at getting the center washers and bushings in place - after removing and re-installing the ailerons a dozen times!
 
You should torque them down. The bolt clamps down on the center sleeve of the bearing and the rest of the bearing rotates around that immobile sleeve. nothing should be rotating on the bolt.

Edit: Forgot to mention- the 20-25 inch pound number doesn't include the friction of a locking fastener. if you're torquing a fiber lock nut you need to bump that number up by the value of the friction resistance of the nut. You can put a bolt in a vise and measure the torque it takes to crank a nut onto it, then add that to the base figure. An AN3 isn't much, so I typically just shoot for 25-28ish and call it good.

Does anyone know the net torque to apply in this instance? AN-3 bolt plus nylon nut?
 
You’re Correct Mel, but….

Manufacturing techniques may vary slightly from supplier to supplier, but torque/tension performance is typically specified and published by SAE or ASTM and should be the same, regardless of the manufacturer. Color of the nylon insert typically identified the manufacturer, and unless specified by the end user, additive torque or use of a lubricant is not necessary or desirable- torque is really a “quick and dirty way” to achieve target tension. Adding more variation on top of thread form, plating, wrench accuracy, nylon, etc. does nothing to help us hit that target. Torque angle is another story.
Terry
(Recently retired - advice may be suspect)
 
Honestly, this is a very bad idea. Unless you are sure you know what you’re doing, or have checked with Vans. Remember a few years back there was a fatal P51 crash at Reno. NTSB blamed it on loose control surface attach nuts.
 
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