Control Cable IRAN

[slowflyin]

I had planned to replace my throttle, mixture and prop controls while I had the engine off my Bravo but I'm having second thoughts.  Now that the engine and mount are removed it seems like nows the time to do it.  The 2k quote from Mcfarland has certainly got me thinking.  My AC came off the line in 1994 and I really don't know if buying new controls is warranted.  I certainly want to replace what's required but I'd like to be sensible as well.  Is there a procedure for evaluating these cables?  After 28 years is replacement a no-brainer??

[N201MKTurbo]

If it ain't broke don't fix it.

If they move smoothly and the ends are in good shape, Why do you want to replace them?

If you can get replacement rubber seals for ends, that would be a good thing to replace.

Edited January 18, 2022 by N201MKTurbo

[PilotX]

Had a prop cable go bad - it is pretty obvious - crunchy feeling. Different plane but that one was around 4600TT. Wasn't particularly hard to pull out, even with the engine in place but I think the cable was only $299, I rechecked ant it went down $35. I am guessing the throttle and mixture make up the difference to $2K?

[slowflyin]

3 minutes ago, N201MKTurbo said:

If it ain't broke don't fix it.

If they move smoothly and the ends are in good shape, Why do you want to replace them?

If you can get replacement rubber seals for ends, that would be a good thing to replace.

Thanks for the quick reply!  I don't want to replace.  I'm more of a Mike B. inspect and repair or replace as necessary kind of guy.  During this process I realized I didn't know how to properly evaluate the condition of these parts and/or the reasonable life expectancy.  I've read post regarding cable failures........

[carusoam]

latest tradition…

Replacement is often done at time of engine OH…

We have seen a reported broken prop control that occurred with an M20R… 

Inspection and recognition of the control issues that can occur is helpful…

 

The gravity of the situation…  a failed control can be the equivalent of an engine out….  Depending on how and where it fails… 

 

Changing the controls at OH is probably early in their life….  But, by the time they get 5k hours on them they are going to have a lot of wear possibilities…

Kind of making changing too early being better than too late…

One of the failure modes to be on the look out for… comes with the rotating knobs…. The cable may start to fray…

And some knobs themselves have fallen apart….

PP thoughts only…

-a-

[EricJ]

My airplane is a 77 M20J, and I think when I got it the cables were all original.    When we changed the prop governor last year we noticed the cable was failing, so I replaced it.   It is *miserable* to replace.

Not too long afterward my throttle cable failed during a flight.  It suddenly started getting very notchy, and jammed twice while on downwind and final.   Def time to change.

It is also pretty miserable to replace, but not quite as bad as the prop cable.

I ordered a mixture cable in anticipation that it's essentially due, given the others failing.   Next oil change, when the oil filter is out, it is getting pre-emptively changed.

They would all be much easier to change with the engine out, but that said, some of the pain is under the panel as well and it wouldn't matter whether the engine was there or not for that part.    Nevertheless, I came to be of the opinion that if the cables aren't reasonably fresh, I'd change them at engine overhaul, which is often what you hear recommended.   That's probably because they're so much easier to change then and if they do fail it can be pretty bad, especially away from home.
 

[RobertGary1]

On 1/18/2022 at 9:15 AM, EricJ said:

My airplane is a 77 M20J, and I think when I got it the cables were all original.    When we changed the prop governor last year we noticed the cable was failing, so I replaced it.   It is *miserable* to replace.

Not too long afterward my throttle cable failed during a flight.  It suddenly started getting very notchy, and jammed twice while on downwind and final.   Def time to change.

It is also pretty miserable to replace, but not quite as bad as the prop cable.

I ordered a mixture cable in anticipation that it's essentially due, given the others failing.   Next oil change, when the oil filter is out, it is getting pre-emptively changed.

They would all be much easier to change with the engine out, but that said, some of the pain is under the panel as well and it wouldn't matter whether the engine was there or not for that part.    Nevertheless, I came to be of the opinion that if the cables aren't reasonably fresh, I'd change them at engine overhaul, which is often what you hear recommended.   That's probably because they're so much easier to change then and if they do fail it can be pretty bad, especially away from home.
 

Do you have the push pull controls or the cool quadrant? I have the quadrant and for some reason it doesn’t seem that it has as many issues. 

[EricJ]

1 hour ago, RobertGary1 said:

Do you have the push pull controls or the cool quadrant? I have the quadrant and for some reason it doesn’t seem that it has as many issues. 

I have a quadrant, which I definitely prefer.    Push-pull might be easier.   One of the difficulties with the quadrant is the way they mounted the cables behind the quadrant.   Really miserable to get to, especially if you just want to get at the prop cable and not disturb the others.