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Rudder cable conduit

rockwoodrv9

Well Known Member
Patron
Has anyone run their rudder cable through the cabin in conduit?
I had a piece of 1/2" pex and it fits the grommet holes perfectly and the cable end fits through it just fine. I have flightline interior panels, but the rudder cable just floating around has always bothered me. I know it works fine, Im just not comfortable with it.

I am not worried about the few ounces weight. I know it isn't necessary. Is there a safety reason to not run the rudder cable through the cabin in conduit?

conduit_zpscermellm.jpg
 
rudder cable cover

I used white cable cover from west marine- it's made for covering mast cables on sailboats. Supports and dresses it up.
 
Are you a mind reader?

I was searching for this topic yesterday.

In my case I am ordering leather side panels with pockets and am considering enclosing the rudder cables to protect both the leather and the cable.

Something stiffer like your solution sounds better to me to guard against the tendency to over stuff a side pocket.
 
Rolivi,
That was my thought too. This is the stiffer pex from home depot. As for inspection, it is easily removed and the rudder cable end slides through it without trouble.
 
You are right - CPVC. Im not re-designing the control system. Just protecting the cable from being squished against the interior panels. If you can give me a safety reason I should not do it, Im all ears.
 
And when I do it

I'll probably go with the CPVC and then glue matching leather around it so it will look sharp.

Then will come educating passengers that it's not a handle!
 
I would never enclose my cables, main reason is: when I open things up I want to be able to see and inspect the cables from end to end. Can't do that if they're enclosed. If my interior panels were hitting the cables I'd modify them so they didn't.
What's the upside to enclosing them?

You are right - CPVC. Im not re-designing the control system. Just protecting the cable from being squished against the interior panels. If you can give me a safety reason I should not do it, Im all ears.
 
Rick, you can see both ends and easily take the cable out for inspection. It is easier to get out of the conduit than it is through the grommets along the rest of the cable run. My interior panels will cover the cable anyway so I won't be inspecting it behind the panel each flight but the cable will still be visible near the rudders and directly behind the seat all the way to the rudder itself. If the cable is going to be damaged, I believe there is a bigger change of damage from something or someone in the seat or baggage area causing the damage. That is why there is conduit - to protect wires or cable.

Do you have interior wall panels is your plane? If not, does the rudder cable ever get snagged on anything from seat belts to headset cords?
 
Rudder cable

With all due respects, I think the next bay back is the more important. My AP required a semi-rigid tube in this area over the rudder cable to prevent any cable slack catching on the Flap Actuating Rod bolt head snagging the cable and pulling it down when the flaps are lowered.
Even more important if, like most of us, the bolt is put in backwards.
This leaves the nut and protruding threads to catch on the cable.
Simple garden reticulation pipe, slit from end to end and bound with gaffe tape in several places, was sufficient to meet his requirements.
Cheers, Rob
RV-7A VH-MyRV Flying.....(0.4 hours)
 
I put mine in 1/4" plastic line all the way front to back. Reasoning was for more protection for the cable from snagging or wearing on anything along the run. No issues in 700 hours.

Greg

P.S. I think it's low enough along the sides nobody would mistake it for a handle of any sort.
 
Here's what I'm dressing up

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I think running it through a PVC conduit with a leather wrap will look awesome
 
First thing is, I agree with Rick Gray. Inspection would be hampered and I don't see the upside. Secondly, CPVC, PEX, and other kinds of poly are not sunlight tolerant so that needs to be replaced every couple years in a bright cockpit. Covering the cable with leather or something will help with the UV degradation, but still cover up a potential problem. One way of checking cables is to pass a cloth (nylon?) over the cable to see if it snags, indicating that the cable is breaking down. It would be easier if the cable wasn't sheathed.

Plus...... I don't see how covering a control cable with plumbing lines meant to go behind the walls of your house dresses up the cockpit...
 
Scott,
I have a complete flightline interiors foam with leather covering with built in armrest going on the wall. You will not be able to see the cable even if there was no conduit over it. Not being able to see it IS the reason I am putting it in conduit. The conduit is there to protect it - the same reason conduit is used everywhere. It will be impossible to damage the cable when it is enclosed in conduit.

After thinking about it more and the post about not getting a certificate in Australia until he enclosed the section in back, I think I will run the entire cable in conduit. No chance of damage, snagging, or being pinched between anything.

As for inspection, I can unbolt the cable from the rudder pedal and pull it completely out from the rudder end outside the plane. Can you do that with the grommets used in the bulkheads? How fun is it to crawl back into the fuselage to inspect the cable?

So, there is no chance of sun damage, it is covered by my interior panels, completely protected from end to end, and easy to inspect. Where is the downside? It will add less than half a bottle of water in weight. Good trade in my book.
 
Wear'n tear?

Good idea, but I'm wondering about wear and tear on the spots where the conduit is passing through the bulk heads?
I'd think that if there's even a slightest movement of the conduit in their bulkhead holes, vibration and movement will start wearing down the conduit at that exact spot?

And if/when the conduit has gotten a hole, then I guess the ruddercable will run directly on the edge on the bulkhead without any protection. And that's not good...

I guess you could glue the conduit in place in their bulkhead holes, but then it'll be difficult to remove for inspections.

Just my 2 cents...
 
Good idea, but I'm wondering about wear and tear on the spots where the conduit is passing through the bulk heads?.....And if/when the conduit has gotten a hole, then I guess the ruddercable will run directly on the edge on the bulkhead without any protection......I guess you could glue the conduit in place in their bulkhead holes, but then it'll be difficult to remove for inspections..

He said the conduit would stay in place and by unbolting the rudder cable at the rudder pedals, the entire cable slides out the rear for periodic inspections. Good idea. Regarding vibrating a hole into it, why would that be any different than doing the same damage to a snap bushing? I like the idea...
 
Regarding vibrating a hole into it, why would that be any different than doing the same damage to a snap bushing? I like the idea...

Because a snap bushing doesn't have any movement or vibrate; it's sitting firmly in it's hole...
 
Because a snap bushing doesn't have any movement or vibrate; it's sitting firmly in it's hole...

The conduit is much firmer in each bulkhead than the snap rings. The snap rings are not nearly as tight as the conduit.

The conduit has no movement because it is tightly cut between the bulkheads and you have to work it to get it through the holes in the bulkheads. There is much less movement of the conduit than the snap rings. A sagging cable sawing back and forward with each push on the rudder pedal will saw through the snap rings many years before it will wear the conduit out.

I added conduit inspection to my annual condition inspection list so I think I will be covered. Im not suggesting anyone else use conduit. I was just looking for things to consider if I used it and I appreciate the responses. Thanks
 
I'll probably go with the CPVC and then glue matching leather around it so it will look sharp.

Then will come educating passengers that it's not a handle!

I've been thinking about things like this for my build and I'm tending to shy away from adding items that can produce toxic fumes during a cabin fire. PVC, CPVC are high on the list of things I will avoid using for this reason.
 
I've been thinking about things like this for my build and I'm tending to shy away from adding items that can produce toxic fumes during a cabin fire. PVC, CPVC are high on the list of things I will avoid using for this reason.

I'm thinking if you have a cabin fire your day is not going to end very well, with or without toxic fumes. It is better to start off with cockpit items that don't or resist catching fire.
 
I'm thinking if you have a cabin fire your day is not going to end very well, with or without toxic fumes. It is better to start off with cockpit items that don't or resist catching fire.

Fair enough but 1. PVC and CPVC still don't meet your criteria and 2. When they do burn they give off toxic fumes that can debilitate you quickly, which could be the difference between a successful, if rough, landing, and a mid air loss of consciousness and death.
 
PVC in the Cabin

I work in the airplane mod business. PVC is not allowed in the cabin for the reasons given. We don't install wire harnesses that have PVC content in the jacket which was difficult at times to find suitable work arounds but not so much any more. Nobody wants a fire in the airplane - it's a bad day for certain. But don't make a bad situation even worse if you can avoid doing so. Do some research on content of materials before you place them in your airplane. I am especially wary of material in proximity of the firewall or near high current conductors. Avoid PVC content please.
Safe flight to all.
 
Suggested material?

I hadn't thought about the fire issue because I'm not encasing something electrical, but does make sense to avoid materials that would have issues with fire even though they are unlikely to be the source of the fire.

Any suggestions for light weight, sturdy, flame retardant tubing?
 
Good point Ben. Taking that advice, I will remove the piece of conduit from the front of the wing spar to the rudder cables. My interior side cards and arm rest are foam covered in leather and if there is a fire, they will likely burn, so the conduit behind them will not be the issue at that point.

To help with fire, I am installing cork on the floor under the carpet. I tried a test with my map gas torch and it is very good at keeping heat away. The aluminum floor will melt pretty quick, but the cork could give me another minute or so. I am debating putting the cork on the engine side of the firewall too. I have not found a way to fasten it to the firewall I am comfortable with so still thinking about that one.
 
....As for inspection, I can unbolt the cable from the rudder pedal and pull it completely out from the rudder end outside the plane....

There's no way I'll have a primary flight control system that I have to disconnect to inspect. That's just asking for something to go wrong, especially if it's at all awkward to access.

On the other hand, a mirror and flashlight might be sufficient to inspect the cable.

Dave
 
There's no way I'll have a primary flight control system that I have to disconnect to inspect. That's just asking for something to go wrong, especially if it's at all awkward to access.

On the other hand, a mirror and flashlight might be sufficient to inspect the cable.

Dave

How often are the control rods inside the wing checked? How about the rod under the seats that control the elevators? They are protected by the wings and seats, so we are all comfortable checking the ends. I would say a cable inside a protective conduit is about as safe from damage as anything else on my plane. I don't have to worry about snags or damage because it is protected. Having the cable inside the conduit eliminates the need for inspection at each flight. Both ends are visible at all times. That is no different than any of the other control systems on the plane.
 
How often are the control rods inside the wing checked? How about the rod under the seats that control the elevators? They are protected by the wings and seats, so we are all comfortable checking the ends. I would say a cable inside a protective conduit is about as safe from damage as anything else on my plane. I don't have to worry about snags or damage because it is protected. Having the cable inside the conduit eliminates the need for inspection at each flight. Both ends are visible at all times. That is no different than any of the other control systems on the plane.

Are you going to pull the cables out of the conduit at every condition inspection? Those plus the pushrods deserve a very careful inspection once a year. I would not want to be disassembling any control system parts unless I were repairing something.
 
Are you going to pull the cables out of the conduit at every condition inspection? Those plus the pushrods deserve a very careful inspection once a year. I would not want to be disassembling any control system parts unless I were repairing something.

You can inspect the ends every time you get into the plane or walk by the rudder. They are not covered in any way. Because of a suggestion about fire and smoke, I stopped the conduit at the front of the wing spar, so the last 2' or so in the foot area is always visible.

If you want to inspect the end and entire cable, you unbolt the end from the rudder pedal and pull from the rudder area. The entire cable - with the end still attached can be inspected by just pulling on the cable. You would have to take the plastic hose where the cable passes from the fuselage out to replace the cable. To re-install, you can push the entire cable - with the front end attached through the conduit all the way to the front of the plane. Try that with just the plastic snap rings.

Im not suggesting anyone do this. It obviously inst needed with the thousands of planes flying just fine with the snap rings. I did it on my plane because I can and believe it is a better solution for me.
 
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