1962 Cessna 182 throttle cable internals and ability to have “play”?

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Johnbo

Pre-takeoff checklist
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Johnbo
This one is hard to describe and I’m struggling to get an A&P to the field to determine what is going on and if there is a safety issue.

there is some very low friction play (3/16” or so) when you push or pull the throttle knob. The rod-end bearing, bolt, nut, washers and throttle arm are all tight and have zero play. The large nut that secured the throttle cable to the panel is tight and there is no play there. The outer sheath is well secured the whole length and does not move. I can feel the inner cable move when someone is crating the play in the cockpit but it only moves at the upper end of the throttle body bracket and rearward into the cabin, the cable below that bracket will not move until the throttle is actually opened or closed.

I am not aware of any kind of connection on the actually wire cable within the sheath so it seems strange that this is behaving in such a way. Is this cable actually a two piece component? Has anyone experienced this before and if so, what was the issue?

thx
 
Bell206 said:
Is this a vernier assist type cable?
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It isn’t.

I can’t seem to post a picture but it is just a friction type with a plain bulb and and locking collar.
 
I noticed it in flight on the way home yesterday; the plane is new to me but I would have noticed it before if it was there. I’ve owned vintage planes in the past and could be one of those things that are normal but I don’t like sloppy controls so I’m trying to get it sorted.
 
Johnbo said:
the plane is new to me but I would have noticed it before if it was there.
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FYI: I've found this to be relative to the owner and aircraft as people tend to prioritize certain areas of "new" aircraft over others as they learn their new aircraft. It's not meant as a negative but in my experience what is there now was usually there before except they were looking at something else that was more important at the time. If that makes sense. But...
Johnbo said:
but I don’t like sloppy controls so I’m trying to get it sorted.
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Since it's not a vernier cable, you'll probably need to replace the cable provided everything you mentioned in the OP is spot on. Standard cables wear/stretch, etc. as you described and give you that play. Sometimes you can reposition the cable sheath mounting and take up that inner cable slack/play, but if excessive will start to mess with the actual throttle rigging.
 
I read this several times, and yes hard to explain. Without seeing it, its very hard to understand. But could this be..............there should be a small amount of "springback" in the cable at full travel. That makes sure you can get full travel. You would feel that when you apply full throttle and it feels like the travel didn't "bottom " out completely. Could that be what you are feeling? Without seeing it first hand, It's hard to identify.
 
Oldmanb777 said:
I read this several times, and yes hard to explain. Without seeing it, its very hard to understand. But could this be..............there should be a small amount of "springback" in the cable at full travel. That makes sure you can get full travel. You would feel that when you apply full throttle and it feels like the travel didn't "bottom " out completely. Could that be what you are feeling? Without seeing it first hand, It's hard to identify.
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That is an interesting idea. if the spring is broken, the play could be the distance in the cable normal under spring tension. I’ll need to try it again to see if I feel the spring when it bottoms out; do you know where the spring would be located?
 
No spring. Just flex in the cable should give you a small amount of what feels like spring back. TMaybe think of it this way. When you are at full throttle, you need to know that you are getting full throttle, mechanically. So the cable has the ability to go just a little bit further than the arm on the carb when the arm hits the mechanical stops. I'm not sure that is what you are experiencing. Just a possible guess.
 
Oldmanb777 said:
No spring. Just flex in the cable should give you a small amount of what feels like spring back. TMaybe think of it this way. When you are at full throttle, you need to know that you are getting full throttle, mechanically. So the cable has the ability to go just a little bit further than the arm on the carb when the arm hits the mechanical stops. I'm not sure that is what you are experiencing. Just a possible guess.
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We called it "bounce." The control is rigged to have the throttle arm at its stop as the throttle knob is still about an eighth of an inch from bottoming out against the locking knob. It's to ensure that you're getting full throttle when you demand it. Prop, mixture and carb heat controls are also rigged this way.

Pushing against the knob and having it bounce back a bit is a function of the cable housing stretching a little. That housing is just a tightly coiled spring.

Now, old controls are known to fail. They do wear out. The internal wire rattles against the housing as the engine shakes it, and the wire gets grooves worn into it that weaken it. Corrosion can rust that wire and the pitting weakens it (makes it stiff to move, too). I've seen at least one throttle cable failure and several carb heat failures, and once I became the Director of Maintenance at the flight school I started replacing all the engine controls at engine overhaul or replacement. Never had any problems after that.
 
Johnbo said:
This one is hard to describe and I’m struggling to get an A&P to the field to determine what is going on and if there is a safety issue.

there is some very low friction play (3/16” or so) when you push or pull the throttle knob. The rod-end bearing, bolt, nut, washers and throttle arm are all tight and have zero play. The large nut that secured the throttle cable to the panel is tight and there is no play there. The outer sheath is well secured the whole length and does not move. I can feel the inner cable move when someone is crating the play in the cockpit but it only moves at the upper end of the throttle body bracket and rearward into the cabin, the cable below that bracket will not move until the throttle is actually opened or closed.

I am not aware of any kind of connection on the actually wire cable within the sheath so it seems strange that this is behaving in such a way. Is this cable actually a two piece component? Has anyone experienced this before and if so, what was the issue?

thx
Click to expand...
I have a 1962 C182 and had something similar before changing out cables last year. We found upon removing the old cable that the outer cable cover had eventually begun to bend and separate the twisted outer wire that was allowing the innermost control wire to bind slightly during use and would cause a slight rapid change when the binding inner cable was given enough pressure. We replaced with new McFarlane cables all around and couldn’t be happier. I expect over time if left untreated the inner cable would have eventually broken. The bend I believe may have been through the firewall and was not visually evident until removed from the plane.
 
Thx folks. I wasn’t comfortable with the cable and found in the logs that it was last replaced in 1989 so I got the vernier assist cable from MCFarlane and wow, what a smooth and precise setup! We found an area on the old one where the sheath was cracked but never did find the source of the play. Replacement was overdue and this new cable is so nice...money well spent.
 
Johnbo said:
Thx folks. I wasn’t comfortable with the cable and found in the logs that it was last replaced in 1989 so I got the vernier assist cable from MCFarlane and wow, what a smooth and precise setup! We found an area on the old one where the sheath was cracked but never did find the source of the play. Replacement was overdue and this new cable is so nice...money well spent.
Click to expand...

Really glad to hear you found the problem as likely the cable or some aspect of cable installation.

The McFarlane engine control cables are so much better built with an inner Teflon sleeve, it will be interesting to see the actual longevity of these new cables. I’m also installing three new McFarlane engine control cables in my 182.
 
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