Torque Value for controls.

[Allen B]

Hey folks. I’ve looked up the torque numbers for the control column and when I use the numbers on the book the controls are really stiff. Even when I use 30% less than the book values. Am I doing something wrong during the installation? For the AN3 nuts the book says 20-25 in pounds. That’s really not much pressure and still the controls feel jammed and stiff. Any advice would be appreciated. Thanks.

[gregc]

Hey folks. I’ve looked up the torque numbers for the control column and when I use the numbers on the book the controls are really stiff. Even when I use 30% less than the book values. Am I doing something wrong during the installation? For the AN3 nuts the book says 20-25 in pounds. That’s really not much pressure and still the controls feel jammed and stiff. Any advice would be appreciated. Thanks.

Can you give us a little more information? Elevator or ailerons? Which bolts/nuts?

[Allen B]

Ailerons. The elevator seems free and clear. There an AN4 bolt connecting the stick to the assembly and an AN3 bolt connecting the push rod to the stick. Both are really tight. Even with 30-40% the recommended torque. I was using 20-25 in pounds for the AN3 bolt and 50-70 on the AN4. I have not put grease into the assembly yet.

[Allen B]

I guess the other question is ‘how free should they feel?’ I have never flown one before so I’m unsure.

[johnhansen]

Good question and one that tripped me up. I assume you’re referring to the AN4-22 and AN3-6 that use castellated nuts and cotter pin. You will find several situations where you can’t torque those type of fasteners to book torque value, since they require movement. Those fasteners are designed for situations with movement. Therefore you tightened them to be snug but not impeding movement, and then insert the cotter pin.

I’m very careful in those situations to double check securing the cotter pin per the guidelines. Those are also in my frequent inspection list to make sure the cotter pin is still secure.

Note that AC 43.13-1B doesn’t cover this situation. The other aviation maintenance handbooks cover this.

[Allen B]

Ok thanks. I’ll tighten them snug and check frequently. How loose should they be? Standard Cessna feeling? And can I assume that the rudder pedal assembly is the same?

[Bcone1381]

I want free movement and no slop in my control.

Using good craftsmanship when installing a castellated nut with a washer and a locking cotter pin results in an assembly that is secure. It wont come apart. I torque my control hardware to at my discretion. If you choose to tighten them so that drag exists in the movement of a control surface, like the elevator for example, it will effect stability.

For example, if the aircraft it trimmed up straight and level, then a short duration push is applied to the stick of 6 lbs of pressure, the nose should cycle on the horizon down, then up, and about 3 cycles then return to normal. But if you tighten that nut to specs so there is resistance and friction and sticksion (stickyness) in the control circuit, when it stick is pushed the nose will point down and it will just keep pointing down as speed builds. It wont exhibit positive static stability...static stability will be neutral. The control just stays where its stuck due to friction. Ask me how I know....Hehehe. .

I tighten mine up until I feel friction, and back it off to feel no friction. It may be backed off one flat. I hope I have no friction and zero slop at that point.

[Allen B]

And when you say ‘free movement’ you mean the ailerons should be as free as the elevator? At this point I have zero drag/resistance with the elevator. If I let go of the stick it would fall forward or aft.

With the ailerons, unless I simply go just beyond hand tight, they are nowhere near as free. Did I miss a step or is that acceptable with the castle nut and pins?

[jaredyates]

In the Bearhawk generally, we are using a cotter key and castle nut if the bolt is the axle. If the bolt is bearing the rotating part and the rotating part is moving like a wheel moves on an axle, then we can't tighten the bolt. Because we can't tighten the bolt, we need to use the cotter key to keep it on the plane. Tighten these bolts based on having the right freedom of movement, just as you will tighten the axle nut on your landing gear wheels. Don't use a torque wrench. If the part is binding at the bolt, then the nut is too tight. Once you are done painting, lubricate these joints initially and then every condition inspection with something like lps2.

On the other hand, if the bolt is not the axle, and the part touching the bolt does not move relative to the bolt. then you can tighten it fully and you do not need a cotter key. Use a torque wrench if you would like. If it is not forward of the firewall, use an elastic lock nut. If it is forward of the firewall, use an all-metal lock nut.

Places where the bolt is the axle, at least on our plane:
Brake pedal-rudder pedal junction
Brake master cylinders (could have a bolt or a clevis pin)
Where the rudder cable shackles are attached to the rudder horn
The control stick pivot for the roll axis
Main gear legs at the top where they join the fuselage
The cabin windows and door hinges (clevis pins/bolts)
On some older planes, the elevator trim pushrod had a fork on one end, and that would require a cotter pin

Places where the bolt is not an axle:
Any rod end bearing, such as the aileron, flap, elevator trim, and control stick pusnrods
On newer planes, the landing gear shock strut bottom. On all planes, the top
All pulleys

Hopefully that makes sense, let me know if not and I'll use more words.

[Allen B]

Thank you! This makes perfect sense. I believe i understood the concept. I definitely needed some validation before committing to loosening the bolts that much. I’ll go ahead and loosen the nuts and lubricate the bolts. Really appreciate everyone’s help with this.

Allen

[jaredyates]

I would not lubricate anything until after you are done with any painting you expect to do in that area.

[Allen B]

Thanks Jared! As far as I know I’m not painting anything in that area. I really like the cream color it came with. I think I’ll leave it as is.

[Bcone1381]

And when you say ‘free movement’ you mean the ailerons should be as free as the elevator? At this point I have zero drag/resistance with the elevator. If I let go of the stick it would fall forward or aft.

With the ailerons, unless I simply go just beyond hand tight, they are nowhere near as free. Did I miss a step or is that acceptable with the castle nut and pins?

It sounds to me like your elevator is better than mine. Good Job.

Attempt to remove all frictionfrom the roll circuit. If the roll control cable was disconnected, will your stick flop over to the left/right? If so, then I trust all your pulleys are new with minimal friction....and I bet your bearings in the aileron bell crank is new w/no friction. And I trust your aileron hinge action is frictionless. If thats the case and you feel some friction in the roll circuit it might be the aileron cable tension. If the cable is on the tight side it will add friction to the system. Too tight of tension changes the way it feels. ALl thos parts....each pulley and each bearing has extra force on it. So Take out some tension and see if that reduces friction.

I also put some of my favorite lubricant on the aileron cable where it passes through fairleads. I like Fluid Film. It will still be doing its job next annual. Good Stuff. But that it pretty much all can think of to reduce friction on the roll circuit..