Broken Mixture Control Cable - Field Repair

[dzeleski]

I recently flew from NY to CA and back, on our way back my mixture control on my 77 J started to have issues with ICO. After calling every shop at KAPA and being told they cant help me for 3 weeks or more I called my mechanic back home and asked for some help. He had an idea what it could be and he ended up being correct, the ball joint failed and the end of the mixture control which caused it to bind up before hitting ICO. He told me to run out and grab some tubing and hose clamps and push the ball back into its socket. Well the temp repair worked great and got us home without issues. I figured I would post up some photos of the issue and the repair in case this ever occurs to someone else.

Looking back on this problem the engine slowly started to have larger and larger issues going to ICO over a few flights, and inside the airplane the mixture control visibly wasn't coming back far enough.

You can see the cable, which you shouldnt be able to, and that ball on the left is supposed to be pressed into the black hole on the right. There is supposed to be a black plastic cover that is crimped over it to keep it in place and you can see that its completely shattered.

Please note: This is not a permanent fix. A new control cable was ordered and installed once I returned home.

Video of the issue:

To fix the problem I bought some 3/8 ID tubing, cut it in half and slipped it over the joint. Then I used two hose clamps to help support the ball joint and keep it together:

Video of the repair:

 

[N201MKTurbo]

I’ve had good luck fixing that with lock wire.

[ArtVandelay]

Assuming your control cables are original, I would consider replacing the throttle and prop cables as well.

I replaced all 3 when I had my engine overhauled, asking cables to work past 40 years old is asking a lot.

[dzeleski]

On 8/25/2023 at 8:07 PM, N201MKTurbo said:

I’ve had good luck fixing that with lock wire.

Didnt think about that I actually keep that in the airplane. I can definitely see that working though.

On 8/25/2023 at 8:25 PM, ArtVandelay said:

Assuming your control cables are original, I would consider replacing the throttle and prop cables as well.

I replaced all 3 when I had my engine overhauled, asking cables to work past 40 years old is asking a lot.

I believe they were replaced during the OH a handful of years ago. Ill double check the books though and make plans to replace them if they werent.

[N201MKTurbo]

The trouble with your vinyl tube repair, is that tubing is only rated to about 65C and it is right over the muffler. That tubing is flamabale too.

 

STANDARD PLASTIC TUBE - PVC vinyl tubing, ID: 1/2", OD: 5/8", Wall thickness: 1.6mm; Hardness: 73A (firm); Temperature Range : 23°F to 149°F (-5°C to 65°C);