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ibjet

Pitch control binding

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I decided to start a new topic because I had mis-titled this and could not figure out how to revise the title.

So, here is the problem: My pitch control had gotten a binding condition. When I moved the Stabilator up it would pop thru a resistance and then when I would lower it, it would go back thru that resistance. I decided to stop flying it that way because it was affecting my ability to flair the plane on landing. 

After a lot of experimenting I finally discovered that the main issue was the Spherical Bearing in the tail had corroded and frozen (would not swivel at all). My CT has apparently spent quite a stint living outdoors. 

I noticed in the Parts & Assembly Manual that the Spherical Bearing had a commercial part number: GE 12 E so I did a search and found a surplus company that had one new for very reasonable (it is a SKF German made bearing). 

For anyone who has this condition, to isolate, you could disconnect the pitch control cable from the bell crank arm and see if it is free to move up and down a bit (mine was not, the spherical ball was frozen in the outer race). Also the dead give away, once you remove that connection, the stabilator travels smoother and the stick front to back motion becomes smoother. 

In the process I made 2 tools that are worth showing:

The first is a tool to compress the spring assembly in the tail. This is so you can disconnect the ball joint that connects the spring assembly to the pitch control bell crank. You need a couple 7 MM open end wrenches to do this, one regular and the other with a near right angle open end (because the ball joint post only has 2 flats on it, not a hex). 

The second is a tool to press out the Stabilator mount bracket axle bolt. It should push out easily, but in  my 13 year old CT it did not. I tried tapping it out and it jammed (big time). I bought a chop saw so that I could make the wood pieces nice and true. 

Eric Swisher shared a link showing what the pitch control cable is made of, thanks Eric! It is supposedly maintenance free except the end rods can be lubed:

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

Speaking of lube, I will show what I bought for that, thanks to recommendation from Roger Lee, you da man Roger!!!

And the last picture is the culprit: The frozen up spherical bearing. 

By the way, all the friction points in the tail needed to be lubed (I used the iNox MX3 with the injection needle, they also make spray, I think the needle version is best).

 

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Axle press out tool.jpg

Axle press out tool installed.jpg

Spherical bearing in housing.jpg

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Edited by ibjet
Gave credit to Eric Swisher, added pic

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Got everything hooked up this evening. Elevator travel is now lighter and smoother, yay, success. So, the main culprit was the GE 12 E spherical bearing in the tail. So, moral of the story: Lube it or lose it, ha ha. I am using that iNox Lanolin lube and for what you cannot reach with the needle applicator, I put a drop on the end of a straightened/clean coat hangar wire, and reach what I want to lube (it wicks in easily). I ended up needing to make a longer base for my axle push in tool so that I could push the axle in. Quite a magic trick to get everything all lined up so the axle will go in. I used the handle shaft of an exacto blade knife as a pilot in the far end to hold that part in line. 

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I use Inox lube on every rodend, hinge and pivot point on every plane every annual. Allowing things like this to constantly move in a dry state isn't your best maint. practice. I see it is very rare that most mechanics fail at this especially when it's so easy. If you followed the checklist it tells you to lube all these points. Of course who uses a checklist. In lies the problem. No list and failure to read.

I just use my spray with the nozzle on the end. It gets to every thing.

 

May not be to bad for lubing a dry sandwich. LOL :)

 

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I used the Inox injector bottle, 60 ml. I was concerned about getting overspray on the composite structure. The injector bottle is also cheaper, maybe that was the tipping point, ha ha. I bought mine from eBay, but I just checked and Amazon carries both versions:

https://www.amazon.com/s/ref=nb_sb_ss_i_1_6?url=search-alias%3Daps&field-keywords=inox+mx3+lubricant&sprefix=inox+m%2Caps%2C235&crid=112FFQPNL6BS9

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4 hours ago, Roger Lee said:

I use Inox lube on every rodend, hinge and pivot point on every plane every annual. Allowing things like this to constantly move in a dry state isn't your best maint. practice. I see it is very rare that most mechanics fail at this especially when it's so easy. If you followed the checklist it tells you to lube all these points. Of course who uses a checklist. In lies the problem. No list and failure to read.

I just use my spray with the nozzle on the end. It gets to every thing.

May not be to bad for lubing a dry sandwich. LOL :)

In that case . . . go with the Food Grade Inox!😀

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