This is no yoke!

[Gone Flyin]

Since taking delivery of my Cessna 150M, there has always been "play" in the yoke on both sides. I found it got tiring having to constantly rotate the yoke back and forth on windy flights so with discussion with my A&P/IA, I looked into what the cause was.

The yoke is connected to the gear that drives the chain that drives the cable by a universal joint to accommodate the slight change in angle of the shaft. It was that part that was causing almost all of the play. The rest by the ovaling of the holes that held the yoke to the shaft.

Replacing that part has made all the difference in the world. The pilot side yoke is now tight and the only play is in the chain linkage, which is minimal, and does not need to be messed with.

There is a rubber boot made from a section of hose that covers the joint but there was no lubrication when it was removed. This may have lead to it wearing as it did, I cannot say that for sure. There is now a high-grade, synthetic, Teflon, non-drying grease inside there.

My flying buddy asked me to look at the yoke in his 150L. He held the passenger side yoke steady while I moved the pilot side.

His was way worse than mine!

There are two pins in the universal joint. One appears to be a strong steel pin that cannot come lose. The other looks to be from a much less sturdy material and that is the one that has all the wear in it. In time, it can shear through IMHO. The joint would fail completely and fall apart under the dash.

If you have this play issue in your yoke (same for the Cessna 170's and maybe others) you should have it looked at. If that universal joint fails you will lose control over your plane.

 

[murphey]

Yup….I had the same joints replaced on the cherokee a couple years ago…they were 51 yrs old.

 

[GeorgeC]

Yup.

https://www.pilotsofamerica.com/community/threads/check-those-u-joints-on-the-yoke.128590/

 

[Dan Thomas]

It's a pain to get under there at annual time, especially in a 150, but I did it. Every time. I have the arthritis to prove it. And I sometimes found worn U-joints, among many other things.

The rubber sleeve was to prevent rattling from vibration, which can accelerate the wear.

We can complain about this stuff, but it's OLD and was never intended to be totally ignored. It's right there in the inspection sheets in the 150 service manuals. Twice, even:





The "control "Y" mechanism is the thing that rocks back and forth behind the panel when you move the elevator. "Mechanism" means everything associated with it. There are oilite bushings in it for the short shafts that carry the sprockets, the shafts that the U-joints turn, and they need a bit of oil once in a while, too. They get stiff. From the same manual:

 

[Magman]

I agree with Dan aka “ other arthritic guy”.

Another place NEVER lubed is Rudder Pedal Pivots.

While Cessna & Cherokee u- joints LOOK similar there is a huge difference in the

replacement effort needed.

Cessna is “ easy” so I have swapped sides to give Pilot the better one.

Most Cherokees use taper pins and require drill /reaming to install .

MacFarlane will rough drill/ team new unit to match old in order to

“ pick - up” hole in shaft. Then you “only “ have to to finish ream under panel.

Extra- special words apply here!

Much easier to lube per SM.

 

[Gone Flyin]

If you look at the second photo in my original posting it is clear there is no way to lube the universal joint without first removing one of the securing bolts. When I removed mine it did not appear there was ever and any type of lubrication inside of that boot, which was tight enough to retain at least some if it had been there.

Anyway, glad to see others have discovered the issue and will pass it on to fellow flyers.

Now, finding someone who can fit under the dash to do the work is their next problem

 

[Dan Thomas]

Now, finding someone who can fit under the dash to do the work is their next problem

For the 150s I had a piece of half-inch plywood maybe three feet long or a bit more. Take the seats out and put that plywood in against the rudder pedals, and lay on it to slither under the panel. It's tight, but doable. Your head will be lower than the rest of you and you might not like that, but this is the only way to fix stuff under there without wrecking your back on that crosswise ridge just ahead of the seats. I suppose one could tie the tail down or block the nosewheel up to level yourself some.

And you'll need reading glasses for any electrical work under there. Your eyeballs are practically against the bus bar and breakers/fuseholders.

 

[Dan Thomas]

If you look at the second photo in my original posting it is clear there is no way to lube the universal joint without first removing one of the securing bolts. When I removed mine it did not appear there was ever and any type of lubrication inside of that boot, which was tight enough to retain at least some if it had been there.

It would have been oiled at the factory when the airplane was built. And that's the last time it ever got any lube. Oil does dry up. After 50 years of neglect, nobody can complain.

 

[Jim_R]

After 50 years of neglect, nobody can complain.

Um, this is Pilots of America: We complain about EVERYTHING!!

 

[Daleandee]

For the 150s I had a piece of half-inch plywood maybe three feet long or a bit more. Take the seats out and put that plywood in against the rudder pedals, and lay on it to slither under the panel. It's tight, but doable.

Whatever it takes! I have a similar piece of wood that I use for the tail cone inside my experimental:

 

[Gone Flyin]

It would have been oiled at the factory when the airplane was built. And that's the last time it ever got any lube. Oil does dry up. After 50 years of neglect, nobody can complain.

Hence the reason to use something a bit more modern than what they had in 1976. A good Teflon-based synthetic grease that will not harden over time.

 

[GeorgeC]

Whatever it takes! I have a similar piece of wood that I use for the tail cone inside my experimental

Thank goodness mom smoked... makes airplane maintenance easier.

 

[Dan Thomas]

Hence the reason to use something a bit more modern than what they had in 1976. A good Teflon-based synthetic grease that will not harden over time.

Yes, the 150M dates from 1974 but that U-joint part number has been in use a lot longer than that.

Modern lubes like the teflon- or silicone-based greases are good. It's the teflon or silicone that lubes, not the oil and thickeners. But the fact remains that these old airplanes aren't getting the care they need, whether it's plain old MIL-7870 oil (such as Royco 363, easily available) or the newer stuff. On top of that, nothing lasts forever. A lot of 150s and 172s and Cherokees have ten or twenty thousand hours on them, and nobody has lubed most of the control system stuff in all that time. I have lubed the pulleys, hinges, chains, bushings, rod ends, bellcranks, and pivots and had the owner exclaim at the fantastic difference in control feel. Even the control wheel shaft and the bushings in the panel should be cleaned and lubed with dry silicone spray. Stuff moves so easily, like it should. One regularly finds cable pulleys totally seized, with the cables sliding over them, abrading both cable and pulley.

As long as owners want cheap maintenance, they will just be deferring the costs until they multiply as stuff wears out and has to be replaced rather than inspected and cleaned and lubed. That gets really expensive.

 

[Magman]

Cheap = Frugal?

Dan nailed that cheap is a dumb move.

“Frugal” owners on the other hand; recognize that deferring many of these items

will cost much more in the long run.

“Frugal” may elect to do many of these items themself as

Preventative Maintenance. Access to the Servicing Section ( Cessna usually Chap 2)

is essential to identify proper materials and techniques.


IA Handbook- sorta quote “The Annual Inspection is primarily a visual inspection. However; it MAY be a good time to have servicing done also.”

Understand that an Annual may not do a lot of servicing chores.

The owner should find out what is and is not done.

 

[Gone Flyin]

But the fact remains that these old airplanes aren't getting the care they need...As long as owners want cheap maintenance, they will just be deferring the costs until they multiply as stuff wears out and has to be replaced rather than inspected and cleaned and lubed. That gets really expensive.

I've been lucky to have had (a few... not all) A&P/IA's that took the high road. Although, I also have had the instincts and enough knowledge to know when some were just blowing smoke.

After all, as the plane's owner I remain the ultimate arbiter for it's continued care.

Unfortunately, those principles are not shared among some of my flying buddies. They rely too heavily on what they're told... or worse... what they're not told about their planes and end up suffering the consequences with high shop bills and lost flying time.

 

[ateamer]

It's a pain to get under there at annual time, especially in a 150, but I did it. Every time. I have the arthritis to prove it. And I sometimes found worn U-joints, among many other things.

The rubber sleeve was to prevent rattling from vibration, which can accelerate the wear.

We can complain about this stuff, but it's OLD and was never intended to be totally ignored. It's right there in the inspection sheets in the 150 service manuals. Twice, even:

View attachment 117661

View attachment 117663

The "control "Y" mechanism is the thing that rocks back and forth behind the panel when you move the elevator. "Mechanism" means everything associated with it. There are oilite bushings in it for the short shafts that carry the sprockets, the shafts that the U-joints turn, and they need a bit of oil once in a while, too. They get stiff. From the same manual:

View attachment 117664

View attachment 117665

So…are you saying that we should follow the service manual written by the company that designed, engineered, and built the plane? What?! That’s just crazy enough that it might work.

I know that my next plane will almost certainly be a regular certified model, and if the current service and parts manuals don’t come with it, I’ll be buying them right quick.