Control Wheels/Yoke Upgrade - How To

[Skates97]

If you have a vintage Mooney you know about AD 77-17-04 which requires removing the control wheels every 500 hours and inspecting the shafts for cracks with dye penetrant. All M20 control shafts are the same outside diameter. People talk about the newer planes having a thicker shaft, the difference is in the thickness of the wall of the shafts, with the older M20's at 0.04 and the newer M20's at 0.06. The difference in the thickness of the shafts obviously results in a smaller inside diameter. The AD does not apply to the thicker shafts.

Every now and then a set of control wheels comes up for sale, offering the opportunity to upgrade your old control wheels and remove the AD. I recently was able to buy a set of control wheels, shafts, and the yoke from a 1996 M20R to put in my M20D. If you have a chance to acquire a set, I highly recommend doing so. I did not think there was much of a difference, and mine actually feel pretty good with the bike tape on them, but once I wrapped my hand around the newer style wrapped in leather I wish I had done it a few hundred hours of flying ago. 

I want to share a few things that you will need to know if making the swap.

The new control wheels mount to the shafts with a bolt going horizontally from 9 o'clock to 3 o'clock. The old control wheels mount to the shafts with a bolt going vertically from 12 o'clock to 6 o'clock. To replace the control wheels and use your old shafts would require drilling horizontal holes in the shafts. Even if you could find an IA willing to sign off on it I feel it would be extremely foolish to add a hole to a shaft that already has an AD to inspect for cracks...

Depending on the shafts that you are buying you will likely have to also replace the yoke. The control shafts have a half circle piece on the end where they attach to the yoke. This piece is what allows the shaft to rotate and provides the stops so that it can't rotate too far. The ones coming off my plane have this half-circle piece on top, centered at the 12 o'clock position. On some models Mooney has the shafts that still had this on top of the shaft, and at one point offered these shafts for sale when upgrading control wheels. I do not believe it is possible to get them from Mooney anymore, and it is likely you will have to replace the yoke. On the ones that I got off the M20R these are rotated 90 degrees with the LH side centered at 9 o'clock and the RH side centered at 3 o'clock. If your new shafts are like that you will have to replace the yoke.

In this drawing that Mooney put out for replacing the control wheels and shafts you can see circled in red the end of the shaft and circled in blue the piece on the end of the yoke that mounts vertically into the shaft.

You can also see it in the parts catalog drawing circled here in red.

I had hopes that I would be able to just remove the ends off my yoke and replace them with the ends off the new yoke, that will not work. The ends are held to the old yoke with a bolt through the end, then through the yoke, and a lock nut on the end of the bolt. The new ends have the bolt integrated into them and are held on with a castle nut and cotter pin. The diameter of the bolt on the new ones is too big to fit in the old yoke. You can see the differences in this video.

Having established the requirement to replace the yoke, here are a few tips for the rest of the project.

• Remove the front seats, you are going to be spending a lot of time on your back under the panel, it's much easier without the front seats in the plane.
• There is not much to replacing the yoke (aside from contorting yourself and laying on your back under the panel) You will have already removed the control wheels and shafts so there are only the two bolts holding the yoke to the tubular frame and the one holding the push rod going to the elevators. Once you remove those you can remove the yoke and put the new one in. (The one off the M20R has a big bob-weight on it. The M20D does not need it so I removed the weight.)
• You do not have to replace the pheonolic blocks that the shafts go through. In fact in my case the new ones won't even mount to my panel. On my plane they are held in place with two screws at the bottom (about 4 and 7 o'clock) and one at the top (at 12 o'clock). The new blocks only have two at the bottom that don't line up with the holes. I had removed mine and had to reinstall which was a waste of time. Take a look at yours in your plane and the new ones before removing them.
• After you have the shafts in, the wheels on, and the shafts attached to the yoke you need to connect the push-rods that go to the ailerons. You will most likely have to adjust the length of them by turning the end to make them shorter so that the wheels are level. You will need to take the slack out of the ailerons before doing this. We used the plane jacks with a piece of wood on them under the ailerons to lift them (lightly) so that they sit even with the flaps. After that you can place a straight edge or level across the shafts and line up the wheels with it. Simply slide the bolt through the shaft and the aileron push-rod (no need to put the nut on yet) and then climb back out from under the panel and see where they are at. Go slow, a half turn at a time of the rod end, put the bolt back through and take another look. Continue to do this until you have them level. Once they are level put the lock nut on and snug them down.
• Make sure you work the new wheels and shafts through their full range of travel to ensure that they do not get caught up on or rub any wiring or the ducts for your vent/heat and defrost. I did this while laying on my back under the panel to make sure nothing was rubbing or binding.
• Because they are M20 parts your IA "should" sign it off as a minor change in your log book. Mine listed the part numbers that were replaced in the log book entry.

(Disclaimer - I am not an AP nor an IA but I did work with mine on this project and this is the process we went through)

I am looking forward to now having a push to talk on the RH control wheel and flying with the new control wheels. There really is no comparing the way they feel in your hand compared to the old ones.

Old control wheel (wrapped with bike tape to make the summers less sweaty and winters less cold...)

New control wheels (Need to make a plate to cover the top of the left side of the right weel)

[Skates97]

I should add that after removing the old shafts I saw that on the bottom side of them they had some wear in them. Granted this is after 55 years of use and it would probably take another 50 years before they could wear far enough to be an issue.

[RLCarter]

Nice write up

[Danb]

Nicely done skates aka Richard

[Hector]

Nice! Thank you for posting.


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[KSMooniac]

Excellent write-up!

I have a set of yokes and shafts for sale if any one needs an upgrade! I've listed them on the FB group but haven't made an ad here yet.

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[Vance Harral]

2 hours ago, KSMooniac said:

I have a set of yokes and shafts for sale if any one needs an upgrade! I've listed them on the FB group but haven't made an ad here yet.

Scott, can you share the part numbers on your yoke shafts?  We're in the market for a replacement, but not particularly interested in a "conversion".  Just looking for an exact replacement for our existing co-pilot shaft, which is airworthy, but scored at the set screw point.

[carusoam]

Great details with pics! Richard!

Thanks for sharing all that.

Best regards,

-a-

[KSMooniac]

Scott, can you share the part numbers on your yoke shafts?  We're in the market for a replacement, but not particularly interested in a "conversion".  Just looking for an exact replacement for our existing co-pilot shaft, which is airworthy, but scored at the set screw point.

Vance, I don't have any part numbers that I can definitely find... The yokes are secured with a horizontal bolt all the way through the shaft and yoke. Does that jive with your configuration?

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[Vance Harral]

12 hours ago, KSMooniac said:

Vance, I don't have any part numbers that I can definitely find... The yokes are secured with a horizontal bolt all the way through the shaft and yoke. Does that jive with your configuration?
 

Unfortunately there's more to it than that.  Among modern Mooney yoke shafts with the thicker walls and horizontal bolt holes, there are still variations in length, and in the orientation of the semi-circular structure welded at the forward end of the yoke.  Many yoke shafts that initially look the same in pictures turn out to have subtle differences, so one really does need to match part numbers to achieve a straight swap.

[KSMooniac]

Ok, I'll take some more pics and measurements of the forward end.

(I'll getting some inquires from the FB listing today)

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[tim417]

Okay, it looks like new yokes for my 63C made it to my upgrade list. @KSMooniac If you still have those yokes and shafts (or a line on some), I’m all ears (and fingers for the credit card number entry.)

[KSMooniac]

Okay, it looks like new yokes for my 63C made it to my upgrade list. [mention=6924]KSMooniac[/mention] If you still have those yokes and shafts (or a line on some), I’m all ears (and fingers for the credit card number entry.)

The pair I mentioned above sold quickly. I currently have a single pilot yoke and shaft from a J, though.

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[randy1]

Does anyone know where to buy replacement control yokes that don't require the AD?  I have a 1966 M20C.  Thanks!  Randy

[wings_level]

55 minutes ago, randy1 said:

Does anyone know where to buy replacement control yokes that don't require the AD?  I have a 1966 M20C.  Thanks!  Randy

I have 66 C as well.  I ordered my shafts from Mooney. I picked up the newer style yokes and just had Mooney make the shafts..  Then I had Aerocomfort to cover the yokes. This photo was when i was getting them installed so ignore the wiring hanging down.

Edited May 27, 2023 by wings_level
Typo

[Skates97]

2 hours ago, randy1 said:

Does anyone know where to buy replacement control yokes that don't require the AD?  I have a 1966 M20C.  Thanks!  Randy

The control wheels (yokes) aren't the problem. it is the shafts. The shafts are all the same OD, but the newer shafts are thicker with a smaller ID. You can do like @wings_level did and get shafts from Mooney or try to find a used set off a newer Mooney that isn't subject to the AD. 

[tim417]

Find shafts from an older J model that match the front ends of your existing ones. You can find them from time to time on eBay, FB groups, or salvage companies. I found mine at Wentworth Aircraft by calling. You can have the factory make them for you as well but be prepared to wait a while and pay a lot. The control wheels themselves are easier to find but can also be pricey. But boy do they update the look of the panel and the AeroComfort leather is so very nice. It’s the one interface that you touch the entire time you fly so it’s something you’ll notice and feel good about each time you fly.