Aileron Control Stops - 4B

[Nev]

What are guys doing for aileron control stops ? Previously I was under the assumption that the control stick fixture provided a stop by limiting the travel of each stick. But on a recent 50 hour check we noted that the aileron linkage was able to contact the aileron hinge mount, so the control stick housing is not limiting movement on that side. I would prefer to have a softer material, maybe bush nylon or delrin. Any ideas appreciated.

 

[AKKen07]

Hi Nev, The limits should be managed by the geometry of the system bellcranks etc. There isn’t a hard physical “stop” in the control stick assembly or elsewhere. In my case I had to carve a curve into my control stick assembly where the stick hit the edges of the fixture - to enable full movement. I guess If you are getting interference somewhere in the system you may need to do something similar. I found a pic indicating where my interference was.

 

[Nev]

Yep mine hits the same place where your finger is pointing on one side. On the other side, the aileron push-rod contacts the hinge mount on the wing.

 

[svyolo]

My assumption was that it was always done by the hinge mount/pushrod. I had to remove some material from the control stick mount. Rescue tape on the rod? A piece of silicone tubing?

 

[jaredyates]

I remember this came up for a Canadian builder who had a regulatory person who required control stops for the ailerons.
This was a discussion from the LSA section but I was thinking there was another somewhere.
https://bearhawkforums.com/forum/bearhawk-lsa-plans-build/27828-aileron-control-stops

 

[Steve W]

For the Patrol,I installed a plate over the rear control stick floor cutout limiting the side to side travel of the control body to the proper amount of deflection. Put a strip of rubber edge protection on each side.

 

[mbaerobat]

The MDRA representative required me to install aileron stops before he’d sign off for flight. I built Dutchman clamps that were attached to the bellcrank support tube to limit motion. A little fiddly to install but serves the purpose. Some thin wall rubber or heat shrink tubing on the stopper could be used to provide a cushion.

 

[Nev]

Nice solution. Graham Johnson has made a very similar fitting with a plastic block attached. Both make for an elegant solution. I was thinking that one per side would provide the limiting I was after.

 

[Bcone1381]

From that idea, springs another....for those who might avoid welding.

Below is pictured the MS27405 tubing clamps. Type A has one lobe. Type B has two lobes. A fitting would be added to the loop clamp to create the stop.

 

[Dpearson]

I've hit this point in my 4A QB project, and haven't solved this aileron stop puzzle yet. I'm not finding anyone selling the MS27405 "Type B" suggested by Bcone1381 . Got some "Type A" on order. My welding skills aren't to the point where I can pull off the "make from scratch" solutions shown by Nev and mbaerobat . Does anyone have any solutions to share, for someone who "might avoid welding"?

 

[Bcone1381]

Try Genuine aircraft hardware. 888-247-2738. They have virtually no website and answer their phone without a menu. They know aircraft hardware. Have them send you there hardware book.

 

[DBeaulieu]

Dpearson Univair had them in the size I needed to make a rear shoulder harness attach point arount the fuselage tubing. I think I lucked out, because they don't make them in a variety of sizes as I found out during my search for them...clamps (MS27405-T5)

 

[Dpearson]

Thanks for the tip! I called GAH and they answered right away. They didn't have MS27405-T6 (3/4" ID) in stock, but the representative was nice enough to do an exhaustive search and eventually found a few at Boeing/Aviall for > $100 per half clamp. Beyond my price range! I will see what I can cobble together.

 

[Bcone1381]

The type A is what I am using to secure a couple of my seat belts to the airframe.  They can be opened up, pressed into place on a tube, then they clamp down on the tube real nice as the bolt is tighted up.

 

[Dpearson]

Here's what I finally came up with for aileron bellcrank travel stops. I used MS27405-6 "Type A" clamps (these are readily available) and 1/2” x 1/8” steel bar, gas welded.​ There's a bit of clear shrink tube over the tabs to provide some cushioning.