Lubing the stabilator cable

[ibjet]

I just recently started flying my CTSW again. It took me "forever and a day" to do my annual (first time, nobody local with a CT or even a Rotax). So, now that I am flying and it's getting cold in Kingman, I'm noticing that my stabilator is sticking when I move it up (I can feel it binding when I move it back toward center travel, not a good thing on short final! I looked at the cable ends and it seems like the best thing is to take off the dorsal fin and remove the cable out the rear of the airplane. QUESTIONS: 1). Is this how to lube it? 2). What lube should I use? I have the silicone paste, thinking that would be good because it will not thicken in cold weather??? 

[FlyingMonkey]

The title of this topic says "stabilator cable" but the stab moves by push rod, so you're actually talking about the two rudder cables...correct?

[Tom Baker]

39 minutes ago, FlyingMonkey said:

The title of this topic says "stabilator cable" but the stab moves by push rod, so you're actually talking about the two rudder cables...correct?

Actually the stabilator is actuated with a Bowden cable. It is a flexible cable inside a housing.

[ibjet]

I am talking about the push/pull cable that operates the stabilator (front to back motion of the stick). It is a cable in a semi-rigid tubular housing. It does have steel threaded rod ends. It is a pretty straight shot from the actuator in the front to the actuator in the back. So, I assumed you could pull it out of the housing and clean off all the old thickened grease. Apparently Roger has tried it or heard a horror story from someone who did. I like the idea of taking off the stabilator. The mechanisms just in front of it are a big mystery to me, so I will really enjoy getting to know them, ha ha. I also assumed that the problem was due to the cold weather. Hmmm, I have a ceramic heater in the hangar, thinking I could remove a seat, and the cover behind it and run that heater for a few hours in the closed up cabin. Anyway, I'm thinking if I don't find a problem in the rear actuator, I can still disconnect both ends of the cable, run it forward as far as safe, clean the front portion and lube it. Then run it back as far as safe and clean the rear portion and lube it. 

I'm thinking I may be able to make a bullet nosed guide that I could slip over the rod end to keep it from jamming??? 

OK, I will proceed with caution. Thanks to all. Roger, you probably saved me from a nightmare, thank you! 

No answers about what to lube the ends with? I think the silicon paste will be a good choice. 

I will let all know how it comes out. 

By the way, my doors which were latching very beautifully, are now getting hard to latch again with the cold weather! Amazing because my door seals are very old and need to be replaced (I have the 2 pieces that I need in bulk length). Almost afraid to do it now! I'll measure the old and new before I do that. Maybe the new will flex easier. 

Happy Thanksgiving guys!

ET

 

[Tom Baker]

I'm pretty sure the cable is an assembly, and the inner portion is not removable. You might be able to remove the rubber boots on the ends and force some lube in side, but my experience with other cables is that it is not going to help much.

I would look for things like the controls snagging on a wire bundle in the tunnel, or the geometry of the pitch servo arm on the AP if installed.

[coppercity]

This is the system used in the CT stabilator control.

http://www.flexballitaliana.com/prodotto.php?idprodotto=80

I had to replace one recently that was binding from I assume internal corrosion.  

 

 

 

[ibjet]

Thank you so much Eric! Wow, never would have guessed that it had ball bearings, amazing. So, I need to disconnect both ends and see if the binding is in the cable! I think I will remove my Stabilator and my dorsal fin (has a crack I need to repair). I guess this is as good a time as any to have my bird in pieces, ha ha. 

Thanks all, what a great resource this Forum is, that's amazing too!

ET

[WmInce]

11 hours ago, Roger Lee said:

I get my INox at Ace Aviation.

Is that food grade?

[WmInce]

Thanks Roger!

[Runtoeat]

I have a similar cable for the steering on my boat.  The name for this cable is "teleflex".  It is normally a sealed unit with teflon lining and sealed telescoping stainless steel ends where it attaches to the rack and pinion and the motor.  These cables are very durable and last for many years on boats exposed to salt water.  The cable Eric has referenced for our CT's looks to be more robust that the teleflex.  I would think this would be a lifetime cable and wonder how this would ever need replacing?  Was there any indication that the cable you replaced was damaged or improperly installed Eric?  Has anyone else found one that needed to be replaced?

[coppercity]

20 hours ago, Runtoeat said:

I have a similar cable for the steering on my boat.  The name for this cable is "teleflex".  It is normally a sealed unit with teflon lining and sealed telescoping stainless steel ends where it attaches to the rack and pinion and the motor.  These cables are very durable and last for many years on boats exposed to salt water.  The cable Eric has referenced for our CT's looks to be more robust that the teleflex.  I would think this would be a lifetime cable and wonder how this would ever need replacing?  Was there any indication that the cable you replaced was damaged or improperly installed Eric?  Has anyone else found one that needed to be replaced?

Hi Dick,

 

No obvious damage or signs of installation issues, just really stiff stabilator movement.  I suspect it had water/humidity intrusion over time that maybe corroded it internally (came from coastal environment and not always hangered).  

[ibjet]

Just caught up on a bunch of inputs here (dang, I didn't have "notify me . . ." clicked). Thanks guys for all the input. 

Well, Riddle me this (ha ha): This afternoon, I removed the cable end connection in the tail. I reached for the stabilator right away, and it moved very freely. So, I went into the cabin and took off the center console covers. But, before trying to disconnect the cable end there, I  moved the control stick fore and aft - it was very free to move also! I hate it when mechanical things baffle me - that's not fair, ha ha. Tomorrow I'll go back to the hanger and scratch my head some more!!! 

[ibjet]

Thanks Roger. The binding has become worse over time. It started about a month ago as a detectable increase in drag when I would move the stabilator in the up direction during my walk around. Yesterday I could feel it in the up direction and in the down direction: fairly easy to move when first starting, but then suddenly a binding feeling as you move it up and then the binding repeats as you move it back toward center (so it's like a binding "spot" in the travel. Then if I move it down, it is the same, hits a binging spot, then binds again as you move it back toward center. I can also feel essentially the same binding in moving the stick center to back and center to forward. 

So, then what blew my mind is: that binding totally goes away when I disconnect the elevator cable (no binding of the stabilator motion and no binding of the stick motion. Not logical at all! Like I said, I'll go back to my hangar today and scratch my head some more, ha ha. 

I guess I will disconnect the trim control and the spring damper and reconnect the elevator cable. Then if the binding is gone, I'll trouble shoot the trim system and damper. Have not removed the stabilator yet, so I'll do that in the process, just so I can say I've done it, ha ha. So far I only removed my dorsal fin (brought it home to repair a crack on the left side, have the correct glass and resin).

[ibjet]

This afternoon I went and tried to remove my stabilator, but that is a bit tricky! I decided if I disconnect the cables, spring carrier, and link arm from the bell crank arm on the stabilator, that I would be able to remove the stabilator with the bell crank and balance weight/arm still attached. 

But, . . . as soon as I removed the trim tab cables from the bell crank arm, the stabilator whammed into the full up position! I thought the spring assembly was spring loaded to center travel, not!!!

I tried pushing the spring assembly piston forward and I could do it, but now I need a way to push it forward and lock it. Being a retired aerospace manufacturing engineer, I can design and make a tool to do that, but I thought I would see if anybody can let me know how they solve this issue.

Once I remove the stabilator, I still won't know what my binding issue is, but this is just what I gotta do!

Roger Lee - Please read my prior posting and let me know if any of this makes sense to you!!!

Season's greetings all, happy flying . . .

ET

 

 

 

 

 

 

 

 

 

 

[ibjet]

Thank you so much Roger, you are sooooo helpful, as usual! 

Still baffled what my "vanishing binding problem" could be. And with the Stabilator removed it will take a lot of force to move the Stabilator mount/pivot. So I might not even be able to feel the binding then. 

I think I have to go ahead and remove that spring assembly. I'll find suitable tubing and slot it like that Safety Alert shows. Then I'll have to come up with a way to hold the tubing against the spring while I work. Hmmm, move over Rube Goldberg, ha ha.

[ibjet]

I did some more poking around . . .

I loosened the nut that holds the spring rod end to the trim arm. Then I tried to turn the ball end shaft (it has 2 flats), the dang thing would not turn! I even pushed forward on the spring to take tension off. I guess it is threaded into the trim arm. It may even be Loctited on. Next time I'll shoot it with my little heat gun first.

For my tool to compress the spring, I found I have some 1" dia alum rod, so I'll make something like the Safety Directive shows about 2 inches long and attach it to a long rectangular piece of hardwood trim. Then, I'll pull the Stabilator down into neutral position and apply that tool, and clamp the other end of it to a stationary table. I gotta do something like that to be able to remove the Stabilator so that I can re-connect the trim cables.

But, I'm accomplishing the mission, learning what makes the Stabilator tick!  

Thanks for your info Roger. 

I'll have to show a picture of my set up when I get to it (multiplexing this week, ha ha).

 

[cdarza]

Your detailed descriptions and pictures are also very much appreciated.     I sure hope i dont have to do what you are doing but if i do,  you are already helping tremendously.  

[ibjet]

Thank you! This Forum is such an awesome resource!

You know, like anything else, if you just pour yourself into it (cautiously, ha ha) after a while of swimming around in it, it just unveils itself. Now that I know how I will compress the spring, it does not seem like that much of a challenge. I have a mini milling machine so I can make little tool details when I need them. But the metal part needed for this could be made of tubing and the slot made with a Dremel motor. I'm looking forward to posting a picture . . . 

[Runtoeat]

I made a tool to remove the spring a few years ago.  Took a 3 foot piece of 1" water pipe, cut a slot in it with my die grinder with small cutoff wheel.  The diameter of the pipe allows it to push on the washer while the slot on one side allows compression of the spring past the ball attachment.  Recall needing to "lean in" to the spring to compress it and then holding it compressed while another person installed the wire to keep it compressed.  Reversed the process to install the spring.  Sounds like the repair procedure is basically what I describe.

[ibjet]

I'm going to use a short length of 1" dia alum bar, but I will connect it to a long skinny piece of hardwood trim that I can clamp to a stationary table (once I get the Stabilator held down into neutral position). I will drill a .50 dia hole thru on center line (that will just clear the head of the ball joint). Then I will mill a flat along the side of the bar until I have a .300 wide opening that will clear the post of the ball joint. That way I will have a pretty big foot print to push the spring forward with, but I can also reach in with a 7 mm open end wrench to turn the post (mine is either Loctited in or just threaded in to the Trim actuator arm. When I try to loosen it, I'll hit it with my little heat gun first to soften the Loctite. Posting a picture showing the foot print of the tool that I will make (in red).  

[ibjet]

I finally got the spring assembly removed. Thought I'd share some pictures. I see a problem already - the spring assembly is not held in place on the FWD end except by a thru hole in the composite material (see bottom hole in pict 4). The center shaft of the spring assembly is way smaller diameter than that hole. I think there needs to be a bushing there of some kind. The parts and assembly manual does not show anything there. Tomorrow I will hook up the elevator cable and trim cables again and see if the binding is still there (without the spring assembly). If so, I will next check into the trim tab and it's linkage. Final chaper yet to come, ha  ha, . . . 

[ibjet]

Yes, thanks Roger,  I have the newer version spring assembly with the guides. Hopefully I will make it out to the hangar and continue my evaluation today.

It just doesn't seem right that the front end of the spring assy is located by a small shaft which travels fwd/aft and it goes into a much larger hole. I actually ordered some 1" dia Teflon rod to make a bushing for that spot. Not sure if I will follow thru. 

[ibjet]

I don't think I will need to do that pre-compressing thing, my set up allows me to compress the spring and go hands free. I'm chomping at the bit to remove my horizontal but by the time I was home from chores, it was 41 degrees, and I just could not force myself to go. Sitting at home in front of my fireplace, ha ha. It'll be warmer here tomorrow and I'll make more progress. 

 

[ibjet]

Removed the horizontal yesterday and it looks like Roger was right once again!!! I had not noticed but the rod end that connects the elevator cable had a very light coat of rust! One of the 2 trim tab actuators has a very tight rod end (I'm betting it is totally dry inside). The full width trim tab (not sure if they have another name for it) is fairly hard to move. And, yesterday I got the iNox MX3 that Roger recommended. I got the non-spray with a drip needle, think that makes the best sense (to avoid getting lanolin on the structure). I drilled a hole thru a 1x4 about 30 inches long and and mounted it as a counter balance for the counter balance, ha ha. 

So, my plan is to clean and lube everything (I'll have to peal off the nylon tape to get to the trim tab hinges) but I have new tape. And, as I reconnect things I will check for binding each time. I will also lube the connections in the cockpit. I will have to do one more final post here to confirm.

But, Roger or anyone who has removed the horizontal tail: What the heck is that extra ball joint for? I removed it from the control arm and it fell out, ha ha. Is this just a spare ball joint? Nice of them, ha ha.

Evening update: I cleaned the spring assembly in acetone and then I re-lubed it with the iNox. When I re-lubed the ball joint, I was amazed. It had been very stiff, it now tilts and rotates MUCH freer. I don't think all the moving parts in the tail have been lubed in many years!  

And, by the way Roger - I also decided to safety wire the spring assembly together, thought about trying to thread the rod end post into the control arm and decided it would be worth giving the wiring a try. It's gonna be real fun getting the wire back off the assembly, but,  say la vie!

Again Roger, thank you for your great help so many times on this forum!!! 

[ibjet]

Still had the binding when I hooked up the elevator cable rod end to the bell crank again! There is a spherical bearing at the rear cable mount bracket. It will not swivel at all. I lubed it with the iNox, but no luck. I also noticed that the cable rod end is not lined up well with the hole in the bell crank. When I force the rod end down during connection, that is when the binding happens. I did a little search (because the parts manual says it is a GE 12 E bearing, and I found it pretty cheap on eBay and bought it (SKF GE 12 E made in Germany). 

In a bit I will go back out to my hangar and try to disconnect the front and rear cable mount brackets and see if I can move the whole cable assembly back far enough to get to the rear cable mount bracket assembly and work on it (free up the spherical bearing or remove it). 

Anybody had this issue?

Anybody move the whole elevator cable assembly back?