Danb

Yoke sticky , hanging up

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What you is recommended when your yoke starts to hang up and hard to maneuver when entering the flare and ground effect. I cleaned the shafts, lubed them first with graphite spray(quite a mess), cleaned again then lubed with LS3. It's somewhat better but not good enough. And help or advice would be appreciated.

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Tri flow is the correct answer. You might want to lube everything else in the system all the way to the elevators too.

Sent from my LG-US996 using Tapatalk

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While you're lubing under the panel, check the little square phenolic guide blocks. Make sure they aren't cracked, broken, chipped, etc 

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9 minutes ago, Hank said:

While you're lubing under the panel, check the little square phenolic guide blocks. Make sure they aren't cracked, broken, chipped, etc 

Hank are the blocks adjustable.

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TriFlow really helped mine. I used the squeeze bottle for the second application and it was less noticeable smell wise. 

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29 minutes ago, Danb said:

Hank are the blocks adjustable.

I don't remember, but the shaft goes through it. I just spray mine . . .

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6 hours ago, Danb said:

Hank are the blocks adjustable.

On the older models, the phenolic blocks are held in with half-spherical aluminum pieces. There are small washers, as spacers, between the tabs of the two spheres.  This allows the ball to 'float' in the spherical holder, otherwise the spheres will hold the shaft so firm that it can't angle itself slightly up and down as you push and pull it through its range of motion.

I believe the new ones are the same, but it is doubtful the factory messed it up if the sticking is a recent occurrence. 

LPS3 is definitely too thick.  I suggest using either LPS1 or silicone spray to clean all of that out and then lubticate with TriFlow (or just reapply the silicone spray every annual.)

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Consider pulling off your belly pan. There could be loose linkages present. This can cause binding and added force to achieve full control surface deflection. The mechanic at my MSC tells me he has seen scary things hid under the belly pan that caused "a sticky yoke".

 

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When my Mooney was new to me, the biggest improvement in elevator stickiness was TriFlow on the bungees where the shaft runs through sleeves at the elevator.

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There may be other yoke bushings. The first one is on a 1980. 

41E7A143-91FC-4394-A819-FE73E61DE112.thumb.jpeg.fc1541f0838a2171cbf882a84b0b86d4.jpeg

This is what is on my F model with the yoke retrofit kit that Mooney sold to me in 1997. 

10A8B93F-BD7B-4E31-8D2E-214EF1BB54A2.thumb.jpeg.191d3fcb2c62e01d95736462d2b830e6.jpeg

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In my "E" I found over-length pan screws on a belly access hatch that contacted the elevator pushrod & added friction.  

 

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Now what!, I've cleaned and triflowed the yoke numerous times, every fitting in the chain, inspected everywhere and it still sticks and hangs up. Just left Weber's MSC they did the same with no success, there contacting Mooney for a new block, this will get pricy I'm not sure if that's what's wrong. Landings are guesswork since it hangs up in the flare.

Any help would be appreciated, totally lost.

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Takeoff the belly pans as previously mentioned and start looking for interference somewhere. It shouldn't be flown in that condition.

Sent from my LG-US996 using Tapatalk

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@Danb, I wish I had good advice or good news for you, but we've dealt with the same problem for a number of years now - a very minor "hitch" that we are absolutely 100% convinced is caused by slight wear on the phenolic blocks where the yoke shaft goes through the panel.  We band-aid it with frequent lubrications, and our A&P/IA is comfortable the aircraft is airworthy.  But the reason we haven't installed new phenolic blocks is that best as anyone who has ever looked at it can tell (this is in a 1976 M20F model), the entire instrument panel must be removed to replace the blocks. :(  It's easy enough to unscrew the fasteners that hold the block in place.  But it can't slide off the back of the yoke shaft without removing a bunch of linkages and wiring, and it won't fit through the hole in the instrument panel such that it can be slid off the front after removing the yoke itself.  We even purchased a spare block at one point from LASAR, but sent it back because we could not figure out any reasonable way to install it - at least not until some future, major avionics upgrade.

My understanding is the problem isn't nearly as bad in other models.  I hope yours is one of them.

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Vance it's not looking good, KSM done that,you can feel it's in the block on copilot side, no clue how much a block is, it seems to me once we get the shaft out the block could be cleaned. The planes only 12 yrs old always hangered how could it get that dirty over night?

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And you're 100% sure it's not hung up on anything under the panel, including the wire bundle that goes through the shaft up to the yoke?

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Yep, you can feel it through the yoke on copilot side it's in the block. 

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Check each rod end in the linkage. They should rotate by hand without binding. Lubricate them with WD-40 if sticky or replace them.

José

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Loosened up the eyeball assembly and the eyeball would not move about, just received a new one it moves freely. Now to install it, the avionics man will do the wiring , looks like unhooking the shaft at the end where it connects to the rods,remove the yoke slide the shaft towards the firewall lower the shaft below the cage  slide off the eye slide on the new one reconnect.

If I'm missing something advice is warranted, I've grounded the plane until resolved.Vance I'll let you know how it goes.

 

 

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Nice update Dan!

Hope this solves the issue.

Can you tell if it is only pilot side, or are both going to get swapped out?

Best regards,

-a-

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Anthony only copilot side, the eye seems distorted therefore can't move freely within the assembly

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I ran through the same issue as @Danb .

My elevator control was slightly stiff, especially when outside temperature was above 80°F or so.

The old eyeballs were almost stuck even though I lubed them at every annual (per Maintenance manual MN123). 

mn123.jpg.de4c7a0cc6b836ec78eab84c0c09fc7f.jpg  

(MN123 rev 12/98)

I replaced the old eyeballs with new ones (P/N 710070-501, real PIA to do...). 

I also noticed that new aircraft (M20U / M20V) still use the same 710070-501 eyeballs.

But their maintenance manual comes with an extra line in the chapter 5 :  P/N 710070-501 must stay dry. It makes sense as it as made of nylon and not metal unlike other eyeballs.

1045605821_man165.jpg.1e1bf2d76e026c47a73e78b6708d219f.jpg

(MN 165 rev A)

Although some of the M20J (s/n 24-0901+ ) and M20K are equipped with the same P/N 710070-501 eyeball, the fact that it must stay dry is absent from their maintenance manual.

I e-mailed Mooney factory support about that, they couldn't care less...

I'm writing this here hoping it can help someone.

Edited by Guillaume

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Gosh G-man, I finally had success once we changed the frozen eyeball, obviously if you changed yours and the issue is still there hmmm? I’d assume you need to try all the items recommended above once fixed let us know the result, good luck I know it’s a safety issue.

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