trim control cable rubbing against plate

[WannFly]

i was taking some pictures today of the control cable SB that might soon turn into AD (Piper SB1313A), and noticed something odd. the actual control cables mentioned in the SB are just fine (apart from 20 years worth of dust)... i found a metal panel plate right aft of the trim wheel that is cracked (getting replaced soon), but i also saw the trim wheel control cable (or whatever it is called) might be rubbing against the metal panel plate. now, this is not something mentioned in any AD or SB that i know of, i also dont want to be the reason for one... so the question is.. can my A&P place some kind of rubber grommet in there to stop that metal wire rubbing against anything metal plate? i have sen similar setup where the electric wires are coming from the wings inside the cabin, may be something like that would work?

 

[455 Bravo Uniform]

No, grommet won’t work if the cable is meant to move, will just wear the grommet and cause additional friction.

I can’t comment beyond that, no knowledge.

 

[WannFly]

No, grommet won’t work if the cable is meant to move.

dang. that trim cable is a failure waiting to happen. u can see some scuff marks on it already, though it is completely possible that it is getting scuffed due to the crack and one side being a little lower than the other side

 

[Skip Miller]

Quite clearly the plane in original ‘perfect’ condition didn’t do that. Get
A rigging expert to assess why this is happening and fix it right. Something is bent or mis-installed. -Skip

 

[PaulS]

That's a no fly until it is fixed, something is whacked and judging from the pic it didn't go out of whack until a short while ago. The crack looks like a cut or split, put there intentionally. My unprofessional opinion, worth what you paid for it.

 

[WannFly]

I have an email out to my A&P , will post back on what I hear. That plate is getting changed for sure, wondering if the trim control cable needs to be changed or not

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[RyanB]

I have an email out to my A&P , will post back on what I hear. That plate is getting changed for sure, wondering if the trim control cable needs to be changed or not

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Will be curious to hear what the outcome is.

 

[bnt83]

No, grommet won’t work if the cable is meant to move, will just wear the grommet and cause additional friction.

I can’t comment beyond that, no knowledge.

There are such things as fairleads, a fixed plastic thing (like a grommet) that can be used to deflect flight control cables a few degrees, I forget what it is. In other words over a certain number of degrees in cable direction change requires a pulley, under that can use fairleads.

http://www.aircraftspruce.com/catalog/appages/fairleads.php

 

[Clark1961]

One thing to be aware of when ordering a new trim cable is that some autopilot installations require a longer cable on the PA-28. I ran into the problem with a largish shop so the knowledge might not be as common as one would hope.

 

[WannFly]

thanks all. I got a response from my A&P. he doesn't think this is an airworthiness item and I wont need a ferry permit. guess I am flying from the avionics shop to my mechanics shop

 

[PaulS]

thanks all. I got a response from my A&P. he doesn't think this is an airworthiness item and I wont need a ferry permit. guess I am flying from the avionics shop to my mechanics shop

Sorry man when I said a no fly, I'd be fine flying that to the shop, what I should have said is I would fix it quickly rather than covering it up and forgetting about it.

 

[bradg33]

thanks all. I got a response from my A&P. he doesn't think this is an airworthiness item and I wont need a ferry permit. guess I am flying from the avionics shop to my mechanics shop

If it's just the trim cable, I probably wouldn't worry too much about a flight or two, especially if you're just moving it to the shop for a fix. If you're really worried about it, set the trim to neutral while on the ground, and leave it there in-flight.

 

[WannFly]

Sorry man when I said a no fly, I'd be fine flying that to the shop, what I should have said is I would fix it quickly rather than covering it up and forgetting about it.

yupp, that's how I took it too, but wanted to make sure about airworthiness anyway. there is no way I am flying around forgetting that. I have to go to my A&P by Feb 7th anyway, thanks to FAA (Piper AD for fuel selector valve placard )

 

[unsafervguy]

I'm working from memory here, my manuals are at home, but I think that cable goes through the center of that hole then around a pulley under the panel between the seat belt hold downs. That's the one that must be removed for the inspection for the sb. My guess is when the ap removes the panel he will find the cable has jumped the pulley. That allowed the cable to rub on the panel and the resultant pull on the panel caused it to crack.

Bob

 

[WannFly]

I'm working from memory here, my manuals are at home, but I think that cable goes through the center of that hole then around a pulley under the panel between the seat belt hold downs. That's the one that must be removed for the inspection for the sb. My guess is when the ap removes the panel he will find the cable has jumped the pulley. That allowed the cable to rub on the panel and the resultant pull on the panel caused it to crack.

Bob

U are spot on about the run, but nothing jumped or is rubbing in or around the pully. I checked those cables since everything else was already out for avionics work, that's when I found the crack.

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[Clark1961]

U are spot on about the run, but nothing jumped or is rubbing in or around the pully. I checked those cables since everything else was already out for avionics work, that's when I found the crack.

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That plate has to be located with a bit of care to avoid the rub you see (as I’m sure you are aware). Factory PA-28 parts are usually bare aluminum. The few replacement formed aluminum parts I’ve seen have had zinc chromate coating.

I’m thinkin’ somebody did a crappy drillnfit job on a replacement part. Won’t comment on inspection other than to say some covers don’t get pulled very often. Pulling the carpet and opening the cable tunnel is rare. The ‘crack’ is puzzling since it isn’t likely that loads or vibration would cause a crack with that appearance. Agree with you that it should be replaced. Doubt it has any structural function and it is mostly under the trim wheel cover but it does protect the cable tunnel from a club footed pax.

 

[Stewartb]

That's the straightest crack I've ever seen. There's more to it that a little cable rub. A rub wouldn't make a crack run like that.

 

[WannFly]

That plate has to be located with a bit of care to avoid the rub you see (as I’m sure you are aware). Factory PA-28 parts are usually bare aluminum. The few replacement formed aluminum parts I’ve seen have had zinc chromate coating.

I’m thinkin’ somebody did a crappy drillnfit job on a replacement part. Won’t comment on inspection other than to say some covers don’t get pulled very often. Pulling the carpet and opening the cable tunnel is rare. The ‘crack’ is puzzling since it isn’t likely that loads or vibration would cause a crack with that appearance. Agree with you that it should be replaced. Doubt it has any structural function and it is mostly under the trim wheel cover but it does protect the cable tunnel from a club footed pax.

yah I am kinda baffled too. I don't know if that part comes off for annual or not, but from now on it is coming off during annual by me when my A&P is around that's for sure. when I examined the cable tunnel for the SB, it didn't look like anyone had cleaned anything in that tunnel in about 40 yrs

 

[Stewartb]

It looks like those two holes were cut with a hole saw, not pressed in during production of the part. What's that about? Maybe whomever cut those holes simply missed their mark?

 

[unsafervguy]

yah I am kinda baffled too. I don't know if that part comes off for annual or not, but from now on it is coming off during annual by me when my A&P is around that's for sure. when I examined the cable tunnel for the SB, it didn't look like anyone had cleaned anything in that tunnel in about 40 yrs

Normally that panel does not come off. The cover over it needs to come off. To remove the panel the trim wheel assembly bolts must be removed and the cable goes through that panel. The one behind it and the one In front should, with a light and mirror you can see everything under it from the front and back. The one that never seems to get taken off is the one behind it, which is where the bracket that Need to be inspected and measured in s/b 1313 is.

Bob

 

[WannFly]

Normally that panel does not come off. The cover over it needs to come off. To remove the panel the trim wheel assembly bolts must be removed and the cable goes through that panel. The one behind it and the one In front should, with a light and mirror you can see everything under it from the front and back. The one that never seems to get taken off is the one behind it, which is where the bracket that Need to be inspected and measured in s/b 1313 is.

Bob

Ok, no wonder there is 40 yrs worth of crap in that tunnel

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[WannFly]

on a diff note, does anyone know if a SB is complied with and then it turns into an AD.. does AD need another sign off saying the SB was complied or does the whole inspection process have to be done? i am asking because, do get this cracked panel thing sorted out, my A&P have to take out a whole lot of stuff, might as well get a sign off on SB1313A since i know its not an issue on my bird.

 

[Clark1961]

on a diff note, does anyone know if a SB is complied with and then it turns into an AD.. does AD need another sign off saying the SB was complied or does the whole inspection process have to be done? i am asking because, do get this cracked panel thing sorted out, my A&P have to take out a whole lot of stuff, might as well get a sign off on SB1313A since i know its not an issue on my bird.

The Airframe mechanic who does the SB can sign off the AD without additional work as long as nothing is added in the AD. It’s a paper chase after the SB is complied with.

 

[WannFly]

finally got this taken care of a couple of weeks back. the trim cable looked like was rubbing, but actually it didnt. A&P said, its not a crack that happened, it was a intentional cut. he suspects the trim cable was changed at one point and hence the cut without taking a lot of things apart (paraphrasing)

 

[SoCal RV Flyer]

A simple fix is a plastic snap bushing. Get one sized for the hole and pop it in. Done.

They're very hard plastic, so there's next to no extra friction introduced to the system. The rudder cables on my RV-9A run through snap bushings in the fuselage bulkheads all the way back to the tail, which is the Van's recommended way.

You can get them from Aircraft Spruce in a bunch of different diameters, but you'd have to make a cut to slip it over the cable. Or get a bushing like this, already split:

 

[JAWS]

Check all of the trim pulleys for wear. Or a bent bracket.

 

[ironnerd]

The cable is an issue, but I'm actually more concerned about the cracked sheet metal. It's time to get a bright light and a mirror and start looking around.

FWIW, I agree with JAWS. Check the next pulley in the system for damage or a bent bracket. The cable may also have jumped out of the pulley.

 

[WannFly]

The cable is an issue, but I'm actually more concerned about the cracked sheet metal. It's time to get a bright light and a mirror and start looking around.

FWIW, I agree with JAWS. Check the next pulley in the system for damage or a bent bracket. The cable may also have jumped out of the pulley.

this was checked by my A/P. no wear on the trim cable or any damage in where in there