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Prp Control No Longer Moves In or Out

Pfatt2

Member
Over the years I have seen numerous examples of prop, mixture and throttle cable control getting harder to move in and out, usually the result of years of getting gunked up. The solution was always to lubricate the cable and all seemed to resolve.

For the last 5 or so flights, my prop control has become increasingly more difficult to push in or out (including by twisting it). As of today, it no longer goes in or out at all. I attempted to lubricate it but to no avail.

I'll take the cowling off tomorrow and see if I find any kinking or other obvious non-governor-related issues. If that is not the case, can the governor be so bad internally that the cable cannot cause the governor to go in or out? Aside from the cable, what else in the hub could be causing this?

Thanks, as always
 
Better than 90% chance this is a cable - disconnect it from the governor and test it that way. I haven’t heard of a governor being a cause of this….but there is always a first time!
 
May be a melted liner in the cable sheath. Re-route the new cable, or add a good heat shield. Best is aluminum or stainless, backed with fiberfrax felt covered with aluminum tape.

These cables are only an inch or so above a 4-into-1, but they have lived 1000+ hours.
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Mystery cable issue

On perhaps my fifth hour of phase one I had a throttle cable jam.

Thank lucky stars that it was on landing and once I had pulled it back to idle it was stuck. Seemed stuck near the engine side terminal so you could see the whole case strain ever so slightly when trying to move it forward.

Eventually got it free on the bench and found that that a certain rotational position aligned the internal binding.

Not heat, no impingement, less than 5 degree bend along the whole length, and ostensibly brand new. Jam was preceded by a dragging feeling near idle that was so slight as to be not quite sure it was happening.

Sent it back to the Company (ACS) for an engineering analysis and never heard from them again. Never did learn the failure mode.

New cable same installation, many happy years of service.

I will forever onwards take the warning signs seriously, even the tiny ones.
 
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Solved

Thank you for the info. I found out first hand what a massive PITA it is to completely de-cowl an RV6A :)

Disconnected the cable from the governor and there were no issues with the governor. It moved with ease (by hand).

The part of the cable that actually goes in and out of the sheath had some shmootz (grease) on it, and I sprayed it with LPS-1, cleaned it up and moved the control in and out, and now the cable moves completely free - much better than it did when I got the plane.

This is a great big PHEW! Now I have to reassemble everything - uggh!

Thank you for the input.

~m
 
I'm not sure there's any RV that's not a chore to decowl, but don't let that dissuade you from doing the appropriate maintenance on your plane!

Had you built it, you would be an expert by now in removing and reinstalling the cowl. It's never painless but there are tips you will pick up by repetition, some of them perhaps unique to your plane. Proper sizing of the intake ramps and baffles so the minimum satisfactory overlap is achieved helps get the front of the lower cowl in place behind the spinner. Anti-Splat sells a protective cover to avoid dropping the lower cowl onto the nose gear fairing and defacing the paint job. Lubed and properly tapered hinge pins help things go back together. And sometimes when you're having a bad day, a helper to keep the far side from falling loose again while you juggle the near side into place makes all the difference. Failing that, a piece of duct tape ]can take the place of the missing helper-holder.

Enjoy flying and maintaining that 6A. Amazing bird!
 
I had a similar issue in February. I had just flown the airplane and pulled the cowl to check the timing, I had been chasing a cylinder temp issue. While putting the plugs back in I noticed the prop cable looked odd, further investigation revealed the cable had failed. The metal sleeve on the end of the cable had separated from the cable itself and was restricting the movement of the cable. :eek:
I attempted to move the control from the cabin, it would move out less than an inch. The prop control had worked fine during the run up and subsequent flight.
 

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