Aileron Pully Question

[Astro John]

The picture is from the build manual. This is the aileron pulley at the top of the wing strut.

Any pointers on how to torque this properly? Is this a case where torquing the bolt head is acceptable?


pulley.jpg

[Astro John]

Also, this is my first foray into using a torque wrench, so I have been researching quite a bit.

Is it really that critical to measure the prevailing torque when using the nylocs? Quite a few of them are in such a confined space, it would be almost impossible to measure.

Generally, prevailing torque for AN4 nylocs seems to be in the high teens.

So, for AN4 with a torque range of 50-70, I'm thinking 80 should be a pretty safe value to torque them to.

[TLyon]

This was my solution to that one, put the bolt in the other way and torque the nut. Works with the bolts point back/down convention too.

I went down the torque wrench rabbit hole too… I ended up turning a few in the vise and got my standard friction adjustments by size. 10 lbs for -4’s sounds about right to me. Also twisted a few off on a stack of washers just to see what the margin for screwing up is. I think -3’s were failing around 95-105 so I’d think -4’s would be fine at 80.

I was going to comment about the cable guard having a lot of space but mine does too. I think I remember something about that pulley being downsized from one kit version to another for better clearance. Something for me to double check tomorrow.

[Astro John]

I was going to comment about the cable guard having a lot of space but mine does too. I think I remember something about that pulley being downsized from one kit version to another for better clearance. Something for me to double check tomorrow.

I checked with Bearhawk on that, and was told the extra space is due to the cable making a slight turn there. The guard is indented at the bottom to make sure the cable doesn't jump the side of the pulley.

[gregc]

Maybe just the photo but I don't see any indentation big enough to have an effect on that large a gap. I would probably drill a small hole across it and use a cotter pin as a guard pin just to be sure.

[svyolo]

I put a -3 bolt and nyloc to make sure the cable is captured and can't slip. Cotter pin works too.

[Bcone1381]

The cable guard does not meet an industry best standard. Don't let the standard slip. Can I make one that fits right for you?

[Astro John]

I appreciate the offer. I'll see what I can come up with first.

[Astro John]

What do you think about fabricating a U-bracket to rivet into the cable guard? The picture is just a crude example piece I bent with pliers.

IMG_8736.jpg

[gregc]

Points for creativity but I would just make one that is the right size or take Brooks up on his offer to make one for you.

[Chris In Wisconsin]

If the parts are already made and it serves the purpose, I don't see a reason to rework it, TBH. As long as keeps the cable from slipping out of the pully when slack and bind up, I'm for it.

[Astro John]

What do you think of this mock up? It moves the flange that keeps it from rotating to the other side. The original is two pieces that are welded together. This is single piece, so no welding involved.

IMG_8748.jpg IMG_8747.jpg IMG_8746.jpg

[DBeaulieu]

Looks great to me...is that a 3D print job? If so, suggest going metal

[Astro John]

Lol, yes, just a mock up to get dimensions and a template.