Aileron Cable Replacement

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norcal64d
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Aileron Cable Replacement

Post by norcal64d »

Well during my whole aileron removal I found some broken strands on the outside of the thimble eye where it connects to the aileron horn. Looking at the service bulletin for the aileron cable routing, they have instructions to replace the cable and it would appear the idea is to cut the old cable at the aileron, then pull the new cable through. Then, the SB says you have to nicopress swage the cable to the turnbuckle up in the headliner area. This sounds like it would be pretty easy to mess up if you don’t get the cable relatively tight before swaging as you have a limited amount of travel on the turnbuckle to take up the slack. Has anyone done this and have any tricks to help the process? It would be fantastic if there was a drop in replacement cable but that doesn’t seem to be the case.

I’m going to call Maule parts when they open and confirm that their replacement aileron cables have one end already terminated and you just have to swage the turn buckle end.
Tim
1991 MX-7-180

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Andy Young
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Re: Aileron Cable Replacement

Post by Andy Young »

I always make my own cables, but I do prefer to make them whole on the bench, then install them. I find it easier to get the length correct that way. With the aileron cable, removing and installing it whole requires removing the bottom half of the split guide block in the fuselage, near the wing root. This can be a bit of a pain, but it’s do-able. You also need to remove the pulley that the cable goes around out in the wing, which is pretty straight-forward. You can then lay the old cable on the bench, and build a new one to match.

There is also a good argument to be made for building them in place; it’s a matter of personal preference.

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Andy Young
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Re: Aileron Cable Replacement

Post by Andy Young »

Be sure to get the ends properly swaged. There is a check tool that comes with most swage kits, or you can measure it with a caliper. The swaged portion MUST be under the specified dimension. Just because it looks good doesn’t mean it is. I know someone who’s newly-built plane had a rudder cable come apart during a landing in a high-consequence spot due to an improperly swaged end. Fortunately, he saved the landing. I was then tasked with checking all the cables (someone else built them) and found that they were all swaged one size too large. Looked beautiful, but….

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norcal64d
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Re: Aileron Cable Replacement

Post by norcal64d »

Andy Young wrote:
Mon May 16, 2022 9:30 am
I always make my own cables, but I do prefer to make them whole on the bench, then install them. I find it easier to get the length correct that way. With the aileron cable, removing and installing it whole requires removing the bottom half of the split guide block in the fuselage, near the wing root. This can be a bit of a pain, but it’s do-able. You also need to remove the pulley that the cable goes around out in the wing, which is pretty straight-forward. You can then lay the old cable on the bench, and build a new one to match.

There is also a good argument to be made for building them in place; it’s a matter of personal preference.
Good info, thanks! According to Maule, they would only send the parts and pieces out, its definitely a build it yourself situation.
Tim
1991 MX-7-180

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norcal64d
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Re: Aileron Cable Replacement

Post by norcal64d »

I'm assuming you have to remove the plastic cable guides as well with the cables if you are building the cables outside the aircraft? They are are about halfway down the wing and appear to be a two piece fairlead held in by a snap ring of sorts.
Tim
1991 MX-7-180

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Andy Young
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Re: Aileron Cable Replacement

Post by Andy Young »

norcal64d wrote:
Tue May 17, 2022 8:34 am
I'm assuming you have to remove the plastic cable guides as well with the cables if you are building the cables outside the aircraft? They are are about halfway down the wing and appear to be a two piece fairlead held in by a snap ring of sorts.
Correct. Sorry; missed that step. Just pop the clip off, and two plastic pieces slide out of the steel tube, which is large enough to allow the thimble on the end of the cable to pass through.

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norcal64d
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Re: Aileron Cable Replacement

Post by norcal64d »

I ended up not removing the pulleys and guides and just built the cables in place. It is definitely a two man job. I’m sure someone will search for this so I will leave a few details here, although I won’t claim to be an expert!

Parts required:
-4x12ft-ish sections of cable, 1/8” 7x19 galvanized or stainless. The advantages of galvanized made it an easy choice for me, but I believe Maule only does stainless now. I suggest 5x14ft sections so so you have some wiggle room, and have an extra length for any mistakes.
-4x AN115-21 shackles, these are the shackles that attach to the aileron horns
-8x AN100-4 thimbles
-28-3-M zinc coated nicopress sleeves or tin coated for stainless
-4x cable turnbuckle ends unless you reuse the ones already on the old cables
-4x aileron rubbing blocks from Maule (riveted in where the cable passes through the wing skin) ($20 each from Maule, they appear to be just UHMW plastic).

Maule SB 12 has good info on how to do the replacement, I followed it and it worked out fairly well. My mistake was turning the ailerons to full deflection to expose the upper cable nicopress sleeves but this resulted in one cable being too short and the ailerons wouldn’t rig. Instead, tape the yokes to a straight piece of wood just like the SB says and when you do the upper cables, have a friend help pull the cables tight and mark where the nicopress sleeve should go. Then, go out to the aileron and take out the bolt holding the shackle to the horn, pull the cable in a few inches so it’s accessible through the headliner and swage the sleeve.

I didn’t many useful pictures, but here is the cable that runs between the bottom aileron horns. You can see that the turn buckle end has the cable swaged on it. Hidden behind the headliner to the right and left are the two cables that run to the top control horns.

Image
Tim
1991 MX-7-180

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