PA-28's .. Excessive Yoke Friction

dell30rb

Final Approach
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Anyone else have issues with the piper's excessive amount of friction at the little gasket / bushing the yoke shaft passes through? I started lubricating it before every flight with silicone and am amazed at how much easier landings have become.

Its like the bushing is made out of rubber or something... when you are using one hand on the yoke you put a side load on this bushing and the yoke really gets difficult to move. All of our warriors have this issue. I'm surprised there isn't a hard plastic bushing available... something teflon coated would be nice.
 
IIRC, the owner's manual specifies a lubricant for that shaft. (Motor oil?).

My old Tomahawk suffered from the same issue and a dab of oil every 3-4 months took care of it.
 
Sounds good. The silicone does not seem to last very long, but it does work pretty well.
 
Anyone else have issues with the piper's excessive amount of friction at the little gasket / bushing the yoke shaft passes through? I started lubricating it before every flight with silicone and am amazed at how much easier landings have become.

Its like the bushing is made out of rubber or something... when you are using one hand on the yoke you put a side load on this bushing and the yoke really gets difficult to move. All of our warriors have this issue. I'm surprised there isn't a hard plastic bushing available... something teflon coated would be nice.
This problem is not limited to PA28s. PA32s have it just as bad. I never noticed it in the Twin Comanche, but the yoke shaft is a bit different in the PA30 (much larger).
 
Every time I change or add oil, I spill a little bit on a rag and run it up and down the yolk shafts. Sounds utterly pornographic, but works like a charm.
 
Odd. I've never noticed a problem in the PA28 I teach in.
 
My yoke make a little squeek, but I have never felt the need to do any more lubrication that the about once a year. It certainly is not any harder to operate.
 
Dad had/has an issue in his as well. I think he just hits it with some silicone spray.
 
We had that problem at the school I trained at. The problem is indeed side load... the weight of your hand on the yoke would cause it to bind significantly.

I told our A&P and asked if we could oil it. He said that oil was probably the reason it bound up so tightly, as the gasket which serves as the bearing below the panel is degraded over the years by the oil. He insisted on using the Piper-approved stuff (and I can't recall what that was... it could well have been silicone.)

I have no way to tell if he was spouting the A&P equivalent of a OWT or not. so FWIW.

-Skip
 
The silicone grease sounds like a good idea. I'll query the club's a&p about it. Would love to see the teflon bushings someone posted a link to installed, but since its a club plane that may never happen.

Things like this really bother me! When I raced motorcycles I was always way picky about keeping my controls lubricated. Lots of other riders didn't really care but I would break out the cable luber every time I washed the bike, and replace cables about 4x as often as other riders.

Now I'm not looking for the competitive edge when i'm landing my club owned piper, but i'm a much happier camper in a machine with smooth, easy controls than in one that squeaks and binds.

It really, truthfully was the cause of a few crappy landings for me as well. Reach over to the throttle and all of a sudden the controls are practically locked up.
 
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I lube my yoke shaft with LPS every so often. That's what Crusty gave me to use.

Spray it at the panel end and spin and push-pull the yoke to get the stuff inside the bushing..

Believe it or not it makes a huge difference in making more squeaker landings. You can't finesse when the yoke is fighting you.
 
Those shafts get sticky because people put their hands on them and leave skin oils that gather fine dust and turn into sticky sludge. The sludge builds up in the bushing. I use a non-chlorinated cleaning solvent to loosen it and blow it out with air. Wipe the shaft off with the solvent, too, then squirt on dry silicone spray. Today I tried some dry PTFE (teflon) spray; we'll see if it lasts longer than the silicone.

Teflon bushings would be no better; they'd gather the same sludge. Best would be the ball-bearing tube guides found in some machinery and in some homebuilts. As usual, homebuilders are ahead in some areas.

Linear_Motion_Ball_Bearings.jpg


One of these, pressed into a radial ball bearing, would allow both push-pull and rotational movement almost totally friction-free. And it would cost a bunch more and weigh more than a plastic bushing, which is probably why we'll only ever see it on homebuilts.

Dan
 
Every Cherokee I've flown has had this problem. An occasional shot of silicone spray lube makes things okay again.

Do not, not, NOT use graphite! Someone used graphite on mine, at some point in the past, and that stuff never, ever goes away entirely. I still get some on my rag, from time to time, after owning Atlas for nine years.
 
I have flown prit near 100 Piper products and I don't recall ever having the problem of too much friction/hard to move flight controls.

From my time in the Cherokee Owners group there was an oft mentioned problem of the yoke having too much play at the bearing.

I've owned 2 Cherokees, I don't understand Steingar's reference of owning in response to Jesse.
 
I've owned 2 Cherokees, I don't understand Steingar's reference of owning in response to Jesse.

In Steingar's opinion most CFIs are idiots when it comes to ownership. This is understandable, since they borrow aircraft fed and housed by others. That is only Steingar's opinion, though it is backed by loads of anecdotal evidence.

If you own an airplane for an extended period of time you become familiar with its "eccentricities". I've met numerous Cherokee owners who had the same issue. I am not surprised that it isn't universal. Neither are leaky sumps, though lots of Cherokee owners have that headache as well. I've met a bunch of mechanics Cherokee owners familiar with the latter. I've not met a CFI so enlightened who didn't already own a Cherokee.

Skyhawks and other aircraft no doubt have their own "eccentricities". I truly hope I am enlightened enough to realize I don't know what they all are. I hope I am sufficiently enlightened to realize I don't even know all the issues of Cherokees, despite owning and flying one for a few years.
 
I have flown prit near 100 Piper products and I don't recall ever having the problem of too much friction/hard to move flight controls.

It's really a matter of degree, and of personal preference.

I really, really like to have the yoke movable with finger tip pressure in the flare, as this allows for micro-adjustability and some real greasers. This is only possible if the yoke shaft bushing has been recently siliconed.

My wife, Mary, on the other hand, flying the same plane an almost equal number of hours, never notices the yoke stiction. She acknowledges that it's easier to land after I lubricate the yoke shaft, but I don't think she cares enough to do it herself. Again, personal preference.
 
I wonder if anyone out there has tried KY for this problem?
 
jesse said:
Odd. I've never noticed a problem in the PA28 I teach in.
steingar said:
Try owning one.
jesse said:
No real reason to when someone else is willing.
steingar said:
Damn parasite.
In Steingar's opinion most CFIs are idiots when it comes to ownership.
It's much easier to judge them then to be them.

As far as me being a "parasite" I doubt that. I generate revenue in the aircraft I fly and have paid a great deal of money over the years to fly them. I've flown 250 hours this year and 120 of that was me paying for the hours out of pocket and the other 130 was me instructing. You'll find 0.5 hours of me being a "parasite" flying an aircraft on the owners dime but that was to give a discovery flight at 6Y9 as per the owners request at no charge.

I've paid out of pocket around $10,000 in rental fees this year. I've also generated about another $15,000 in revenue for the rental folks.

My statement was just that. I haven't spent much time in PA-28s, only about 200 hours in 8 different aircraft, but I've yet to fly one where the yoke moved anything but freely - based on that - it's perfectly reasonable for me to say "Odd. I've never noticed a problem in the PA28 I teach in."
 
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Try owning one.
I own my '73 180. Don't have this problem. Standard part of preflight is to pivot the elevator...I'm always able to give it a nudge and let go, and it will continue to travel up or down after I've released it. Yokes move smoothly with fingertip pressure.

Didn't realize I was a lucky one. Now that I've typed this, I'll probably start having problems... :)
 
Mine got to the point where it was taking real effort to move it. My mechanics at Gibbs took care of it.

The difference was amazing. It's one of those things that progresses a little at a time, so you don't really notice it until the problem becomes blatant.

John
 
I have noticed similar issues with the 172s I've been training in; trying to pitch to produce a stall with one hand sideloads the yoke enough that it binds a little. This does not occur if you repeat the maneuver with both hands on the yoke.

What are the bushings typically made out of? I'd probably lean towards using silicone lubricant since oil and plastic often don't mix.

I suppose it could be a wear issue rather than a lubrication issue, as well.
 
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Mine got to the point where it was taking real effort to move it. My mechanics at Gibbs took care of it.

The difference was amazing. It's one of those things that progresses a little at a time, so you don't really notice it until the problem becomes blatant.

John

What did they do to it?
 
I have noticed similar issues with the 172s I've been training in; trying to pitch to produce a stall with one hand sideloads the yoke enough that it binds a little.

What are the bushings typically made out of? I'd probably lean towards using silicone lubricant since oil and plastic often don't mix.

I suppose it could be a wear issue rather than a lubrication issue, as well.

It's a bit different in a Skyhawk... the most commonly overlooked thing in Cessnas is lubricating the cables and pulleys in the tail, not so much the quad-bearing thingy the yoke tube rides through.

Just by chance... Cessna Pilot's Association just covered Skyhawk Annual Inspections/Maintenance this month in their magazine, and mentioned a number of small things that are constantly missed that they see when folks turn to them trying to figure out what's going on.

The cable/pulley lubrication thing in Cessnas is mentioned strongly in the article, and was mentioned numerous times in the 182 Tech course I took last year. To say they're on a "campaign" at CPA to get the word out about it, might be a touch strong, but it's definitely a repeating message from them right now.
 
Isn't there an AD or SB out on improperly assembled yokes or bushings? I seem to recall that the Arrow I used for CFI training had to be down for an inspection of the yoke.
 
What are the bushings typically made out of? I'd probably lean towards using silicone lubricant since oil and plastic often don't mix.

I suppose it could be a wear issue rather than a lubrication issue, as well.

They appear to be made of PVC. Very common stuff. It really doesn;t matter what they're made of; it's the sludge that builds up on them, as I said earlier, that makes them sticky. Nothing less than a linear ball bearing will perform better, and even that will get sludge in it.

When I used to design and build machinery, I tried to use pivoting mechanisms everywhere possible rather than sliding mechanisms. Sliders are far more trouble and have more friction to start with. They're harder to keep clean, and any seals add huge friction. Take a look at the older airliner control columns: All pivots, no slides.
800px-B747-cockpit.jpg


Dan
 
It's a bit different in a Skyhawk... the most commonly overlooked thing in Cessnas is lubricating the cables and pulleys in the tail, not so much the quad-bearing thingy the yoke tube rides through.

Just by chance... Cessna Pilot's Association just covered Skyhawk Annual Inspections/Maintenance this month in their magazine, and mentioned a number of small things that are constantly missed that they see when folks turn to them trying to figure out what's going on.

The cable/pulley lubrication thing in Cessnas is mentioned strongly in the article, and was mentioned numerous times in the 182 Tech course I took last year. To say they're on a "campaign" at CPA to get the word out about it, might be a touch strong, but it's definitely a repeating message from them right now.

We run three 172s. WE lube the pulleys maybe yearly and the hinges every couple hundred hours. The control column has to be cleaned every inspection (ten times a year) or the elevator gets sticky. Much more trouble than the rest of the system.

That said, every older airplane we get in here has seized or nearly-seized pulleys and worn hinges.

Dan
 
I'm glad I'm not the only one to notice this problem. It seems to be the worst in Cherokees, though the really old ones with the butterfly yokes do not seem to be as bad. I've also experienced it on Cessnas but it doesn't seems quite as common.

I've found it nearly impossible to make a perfect landing in airplanes with sticky yokes. I don't understand why the other people who fly them don't notice or do something about it. Many are flight school airplanes...and instructors wonder why their students can't land.
 
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Anyone else have issues with the piper's excessive amount of friction at the little gasket / bushing the yoke shaft passes through? I started lubricating it before every flight with silicone and am amazed at how much easier landings have become.

Its like the bushing is made out of rubber or something... when you are using one hand on the yoke you put a side load on this bushing and the yoke really gets difficult to move. All of our warriors have this issue. I'm surprised there isn't a hard plastic bushing available... something teflon coated would be nice.

The problem is not restricted to Piper aircraft - had the same thing in my 182 some years back. It messed up my landings until I figured out what was going on. I used a Teflon-bearing grease.

Dave
 
I owned a Cherokee for nearly 10 years. Just keeping the shafts clean and a little silicone spray or DC-4 silicone grease kept the yokes free and easy to move for me.
 
I'm going to give silicone grease a try. I pulled the yoke all the way out on one of our pipers last time I flew it, sprayed the shafts with silicone spray and scrubbed it with a paper towel. Worked great but next time I flew the aircraft (one week later) it was sticky again so I had to re-lubricate it.


Maybe the grease will last a bit longer. At least a tube is small enough that I can keep it in my flight bag - its difficult to keep up with a spray can.
 
I'm going to give silicone grease a try. I pulled the yoke all the way out on one of our pipers last time I flew it, sprayed the shafts with silicone spray and scrubbed it with a paper towel. Worked great but next time I flew the aircraft (one week later) it was sticky again so I had to re-lubricate it.


Maybe the grease will last a bit longer. At least a tube is small enough that I can keep it in my flight bag - its difficult to keep up with a spray can.

Inside the bushing you would find a buildup of sticky sludge. Without getting that out any lubricant will be only temporary, and any lube, especially oils and greases that attract dust, will add to the sludge.

Dan
 
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