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Aileron cable problems

Skywagon185

Skywagon185

MEMBER
Bigfork, MT
Having some wear problems on these fairly new (5 years) aileron cables, PA-18. Seems as though they are wearing and fraying from the nylon bushings on the struts. Same on both sides. The service manual indicates cable tension as not too tight and not too loose when rigging. Any idea why this may be happening? Seems like the bushings should be wearing before the cable does but they clearly are not.

https://goo.gl/photos/Q1sP5uuTqAmx81ho9

Thanks for any information.

Mike
 
Had the same problem with mine using stainless cables . The strands were getting very flattened from the wear against the fair lead .Turned out that the cables were way lose and dragging in the lead as they bowed out in the slip stream and especially in a turn ..I tightened the cables a bit to stop the bowing and they are not dragging now so keeping an eye on the situation .Cables tested at about 17 lbs before they were tightened to 26 lbs .
 
I am with Mike, but my fairleads are Teflon. Stainless may wear faster - I get decades of daily flying out of one set of cables.
 
We see it a lot- not uncommon to change them every 500-1000 hrs especially if stainless. It's weird but the softer fairlead material usually wears the cable, and not the other way around- see this a lot in Beaver rudder cables where they go through all the phenolic fair leads under the floor... Have seen all fairlead materials do it, but the plastic ones on the cub struts seem especially bad, but I suspect that's more of a tension/vibration issue...
 
Thanks for all the responses. I've learned something today. Univar the best place to get these cables?
 
Last edited:
I had a 1982 model Super Cub with 1500 hours. It left Piper and went straight to Edo to have floats fit. It had stainless cables and consistantly had the aileron cables replaced at 500 hours. My experience has been like your, wears at the first fairlead. I have seen them tight and loose. I replace with galvanised. Have seen the rudder cables on newer Cub Crafter data plate Super Cubs wear at the fairleads and the fuselage exit in a little over 500 hrs. I believe galvanized wears better and after talking to a friend who works for the airlines believe that control cable is not as good as it use to be by the frequency of cable replacements they are seeing.
 
Skywagon185 said:
Thanks for all the responses. I've learned something today. Univar the best place to get these cables?
Click to expand...

Mike, Univair usually has these fabricated and ready to go, and they do a good job on cables. You could do it yourself, of course. Setting tension is important, but you knew that.

Thanks. cubscout
 
ak49flyer said:
We see it a lot- not uncommon to change them every 500-1000 hrs especially if stainless. It's weird but the softer fairlead material usually wears the cable, and not the other way around- see this a lot in Beaver rudder cables where they go through all the phenolic fair leads under the floor... Have seen all fairlead materials do it, but the plastic ones on the cub struts seem especially bad, but I suspect that's more of a tension/vibration issue...
Click to expand...
Soft materials tend to "hold" grit and dirt that is real abrasive and wears the cable. Take a look at most baffle. The rubber wears The aluminum.

weasel
 
RCharles said:
..I tightened the cables a bit to stop the bowing and they are not dragging now so keeping an eye on the situation .Cables tested at about 17 lbs before they were tightened to 26 lbs .
Click to expand...

I was thinking that the last time my cables were adjusted the tensiometer was set to 15#..? They seem too loose now. What is the book setting on these? Is there a way for me to check them without a tensiometer ie measured pull with a fish scale - before I go pay a mechanic to check them. I think I read that you can adjust by setting ailerons 1/2” high and then tighten lower cable to pull down in place? Does that work?

thanks for any info?
 
old sage once told me, you should be able to turn the top strut aileron pulley with your thumb and finger if you cant its to tight.
 
MoJo said:
I was thinking that the last time my cables were adjusted the tensiometer was set to 15#..? They seem too loose now. What is the book setting on these? Is there a way for me to check them without a tensiometer ie measured pull with a fish scale - before I go pay a mechanic to check them. I think I read that you can adjust by setting ailerons 1/2” high and then tighten lower cable to pull down in place? Does that work?

thanks for any info?
Click to expand...

They always loosen up. I like to set them tighter a day ahead of time. Work them some, then loosen and safety them. Or else you will need to redo them and tighten soon


Sent from my iPhone using SuperCub.Org mobile app
 
mike mcs repair said:
They always loosen up. I like to set them tighter a day ahead of time. Work them some, then loosen and safety them. Or else you will need to redo them and tighten soon


Sent from my iPhone using SuperCub.Org mobile app
Click to expand...

I guess they were set to 40 LBS, but I’m going to have them rechecked. I never used to see a perceptible bow in the cable when being used, but now I do.
 
MoJo said:
.... I never used to see a perceptible bow in the cable when being used, but now I do.
Click to expand...
How much time has elapsed between "never used to see a perceptible bow in the cable" and "but now I do."?? Did you actually notice the change or just become aware of bow in the cable?
Has anyone changed or adjusted something in the system during this time? If the answer is no, then it is time to be suspicious. The cable does not usually stretch after it's initial set. Something is happening such as a pulley wearing in it's groove. Perhaps the pulley is frozen and the cable is sawing the groove? Perhaps there is a faulty swage which is slowly slipping? Have the bolts which connect the ends of the cables to the aileron horns become worn? How is the bolt and it's hole at the bottom of the control stick horn under the floor? Are the pulleys at the side of the fuselage frozen in place? A little wear in several places becomes cumulative.
 
skywagon8a said:
How much time has elapsed between "never used to see a perceptible bow in the cable" and "but now I do."?? Did you actually notice the change or just become aware of bow in the cable? .
Click to expand...

Three years - 300 + hours. One of my cables was replaced then. I don’t think the tension has been changed since.

Good question. Maybe time has given me time to notice.

From my inspection, except didn’t look at attach bolts. Nothing is loose, broken, or oval, and all seems to rotate as it should. The only thing that changed recently is I went to smaller tires, and might be flying a bit faster on a regular basis.

how much stretch or wear is common?

Cub has a date with a tensiometer.
 
I seemed to need new cables at about 500 hours in the cub- but my flying was low looking into bottomed of canyons using steep turns. Lots of cranking.

An old and wise mechanic taught me to have a look out at the strut in flight and if it has a slight bow in the cable that is the setting. The down side is sometimes it will chatter with the strut and chip some paint, the upside is the stick pressure is minimal. Tight cable means more stick pressure, which I never liked.
 
They get loose when it chills lots. Set them for expected temps or they'll wrap around the rear strut up from the fork.

Gary
 
If the cables are too loose the aileron response will be sluggish and the ailerons will not move to their travel limits. This in turn will encourage you to spend money on a set of VGs to correct the aileron response complaint.
 
I have seen consistantly 500 hour aileron cable replacements on Super Cubs with stailnless aileron cables. They fray where it intersects the first fairlead up the strut. My aileron cables are slack but the controls feel crisp and full travel is obtained. Tighten them to 35 lbs which seems to be published somewhere and see what you think, then back them down to 15 lbs or so and compare.
 
Steve Pierce said:
Tighten them to 35 lbs which seems to be published somewhere and see what you think, then back them down to 15 lbs or so and compare.
Click to expand...

Haven’t been near my flight manual, so I don’t know if there is a number in there. The inspection form that my mechanic uses says 40lbs. I wonder if that form is/was written for late model Cubs? The thought of 40lbs hanging on any of these 1953 pulleys :Gscared::Gscared:, and I’m hearing numbers of 15-40lbs.

What should they be set at to be legal, insurable, and real world safe? If they need changing, I have to pay to get these done, so I only want to do it once.
 
Tighten them to 35 lbs which seems to be published somewhere and see what you think, then back them down to 15 lbs or so and compare.[/QUOTE]
This is similar to what my mentor said. Tighten it down until the stick gets stiff. Then loosen it a bit at a time until the the stick is free. There was a caution about going too loose and slack in the cables.
 
I strongly recommend changing after 500 hours. Mine were long overdue and were in ugly condition.

They new cables were set at 30lbs but the port wing showed vibration of the cable near the root wing spar attachment, in cruise (85 MPH IAS 90 HP Metal prop)

Have added some protective speed tape but will need to re tension this side to 35 lbs. Starboard cables not affected, but guess this is due to propeller pulses coming round the fuselage on the starboard side.

I am not able to post a video link as I don’t have a relevant video account.
 
L18C-95 said:
Have added some protective speed tape but will need to re tension this side to 35 lbs. Starboard cables not affected, but guess this is due to propeller pulses coming round the fuselage on the starboard side.
Click to expand...
You do realize that the cables starts at the control arm on the bottom of the stick torque tube between the passenger's feet and proceeds out to the aileron, across to the other aileron and back to the control arm in one big loop. The tension will be the same through the entire loop. It will not be different on one side from the other.
 
skywagon8a said:
You do realize that the cables starts at the control arm on the bottom of the stick torque tube between the passenger's feet and proceeds out to the aileron, across to the other aileron and back to the control arm in one big loop. The tension will be the same through the entire loop. It will not be different on one side from the other.
Click to expand...

Static. Sitting on ground.

In flight might have a difference (rigging of plane, controls......)
 
The only wear I have seen has been on stainless cables. My cables tensions are half your tension and with an 82" prop I don't see much deflection and doesn't hit my struts.
 
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