Patrol Elevator Controls

[noema]

I finally got started with my build and it's generally going well. I hit a bit of uncertainty with the torque tube and the elevator push/pull tubes. There is not much info in the manuals and the plans on this. Some of the issues could be caused by this. Can I ask some of you Patrol builders to double-check my install and clarify things for me?

The front stick seems to be ok. I used an AN3-5A with only one thin washer and clamped the bushing from rotating with a low-profile lock nut. The stick is not perfectly centered but there seems to be just enough clearance for the bolt/nut not to touch the torque tube. I wish it had more clearance so the nut/bolt would be further from touching the tube. But I guess this is correct?

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Then on the rear stick I have quite a bit of sideways tilt. When I simulate resistance the bottom of the stick moves enough for the nut to touch the torque tube. Basically the stick's hinge point has too much sideways play.

Video: https://youtu.be/1mKq37DWMU4

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Also the push/pull tube is centered in neutral position but deflects quite a bit to the left on right aileron.

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Finally the push/pull tube rotates on the rear aurora rod end thread. Is this correct and intended?

Video: https://youtu.be/ALl908nwA4Y



Appreciate your input and hope this is helpful for future Patrol builders.​

[BravoGolf]

The photos are behind google login and not visible. A least to me anyway

[noema]

That's strange. I uploaded the photos to the forum. Is it the video links? New video links added.

[spinningwrench]

Scott there are a number of issues you are dealing with that most Patrol builders hit. The Aurora rod end bearing does rotate in the push pull tube. Bob indicates he is OK with this however my A&P inspector was uncomfortable with this. The fix is to get 3/4" clearance in the swing arm. Most builders bend the arms to get enough clearance. I didn't really want to bend a critical weldment to achieve this and wanted parallel arms so I just welded a new swing arm with 3/4" clearance and the Aurora bearing can now be securely be tightened with a jam nut to the push-pull tube. Everything works well. I have jigs for making a new swing arm. The clearance inside the torque tube is extremely tight for the stick connections and one must use a thin nut to make it work. I have detailed drawings of what I did if you want to message me with your e-mail I can send those. I have other suggestions for you as well to consider.

[noema]

Ok, that's interesting. The push/pull tube *is* allowed to rotate on the Aurora rod end thread. This would be important to have in the build manual. Option two is to modify the idler arm to provide more space to the Aurora rod end to rotate laterally. Then it can be locked with the check nut and the aileron input rotation occurs only in the rod end (not the thread). I understand.

To clarify my issue about the bolt/nut rubbing on the inside of the torque tube. This seems to be specific to my parts. In principle I do have enough space in there. The reason it touches is lateral slob in the hinge point of the rear stick. I measure about 0.175" (4.5mm) sideways movement at the bottom of the stick when I simulate aileron resistance. Any ideas how to fix this short of replacing the rear stick or welding in a new hinge tube into the stick?

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[N942VT]

Yes, the rod end rotates on it's threads, get rid of that check nut and make sure there's plenty of thread engagement. Lube it up with never seize and don't worry about it, Bob engineered it to work with plenty of structural margin.
I think the only way to get rid of that slop is to weld in a new bushing, or ream and sleeve. Pretty hard to have zero clearance there though.

[noema]

Thinking of lathing down an AN5 for perfect fit before I get out the welder.

[spinningwrench]

So are the bushings in your rear stick oversize? Not sure where your excess play is coming from?

[noema]

Yes the bushing seems to be on the big side. Also my bolts are on the low size of the spec.

[Bcone1381]

Oversize bolts exist......bolts with a slight larger diameter shoulder....something like .005 over size. I don't have a supplier though. Maybe someone here knows where to search.

[spinningwrench]

It’s too bad your stick bushings we’re supplied oversize. I would probably repair them by adding some braze material to the bore and then reaming to size. Ream just .0005” oversize to the bolt. You would want to develop a simple jig to hold the stick in the perfect vertical orientation for reaming. Best done on a milling machine if you have one.

[Bcone1381]

To clarify my issue about the bolt/nut rubbing on the inside of the torque tube. This seems to be specific to my parts. In principle I do have enough space in there. The reason it touches is lateral slob in the hinge point of the rear stick. I measure about 0.175" (4.5mm) sideways movement at the bottom of the stick when I simulate aileron resistance. Any ideas how to fix this short of replacing the rear stick or welding in a new hinge tube into the stick?

I checked mine...I see what you mean.....I see a little extra slop in the rear stick's hinge. The further the stick moves away from center position the migration and the slop may be too much. When the aileron cables get hooked up it will limit stick travel and I wonder if the issue willresolve itself then.

[noema]

Not really. The rear stick just independently moves sideways too much. When there is resistance on the torque tube (like it would with aileron pressure) it first tilts independently causing the illustrated movement within the tube. Looks to me I just need to increase the precision of stick's hinge point one way or another.