Fixing the yoke shaft

[Echo]

Used shafts are redily available on "The Ebay".  Nice job of salvaging the landing and NOT bending metal.  Maybe I would pony up if that happened to me?  Ya, I probably would spring for the pilot yoke if that happened to me.

[Utah20Gflyer]

On 2/25/2024 at 11:46 AM, Vance Harral said:

Do you have "late model" rams horn yokes? on your airplane?  If so, you're not going to find what you're looking for in the M20F IPC, you have to look in the M20J IPC.  The set screw is documented in section 27-30-00, it's an AN565-D416-H4.

We applied a very light fingertip "dab" on one side of the threads, similar to what one does with anti-seize when installing spark plugs.  It's entirely possible that you used less of the stuff than we did, and that you'll have no trouble later on.  But when you start getting into a debate about fractional differences in the amount of thread locker you apply being the difference between damaging a yoke shaft on the next removal, I'd argue it's not worth it.  The set screw is not a structural item, and the yoke isn't going to come off the shaft if the set screw is loose and allows some slop.  It's just annoying if you're trying to do something like hand-fly a smooth set of lazy 8s.

So coincidentally my yoke started having a little bit of play in it again so I decided to try removing my lightly loctited set screw and then re torque it.  It was fairly stiff coming out which made we worry just a little but I got it out fine, cleaned it up and replaced it, but this time didn’t use loctite.  I’m going to see how long it takes before it comes loose again. If it reoccurs quickly I’ll probably reinstall with loctite again.  Once again using the minimum amount possible.  

[47U]

2 hours ago, Utah20Gflyer said:

So coincidentally my yoke started having a little bit of play in it again so I decided to try removing my lightly loctited set screw and then re torque it.

The factory has replacement yoke shafts in stock (as a few weeks ago) which retires the 500 hr NDI yoke AD… call around to a few of your favorite MSCs for the best pricing.  The difference in the tubing wall thickness between the old and new shafts is significant.  Plus, it’s about 1.5” longer than the old yoke shaft giving you more clearance to the panel should extreme maneuvers be required (like inadvertent spin recovery).  With my left-side panel upgrade, I lost some of that clearance.  And, you can tighten that set screw down to the standard torque value without worry.  

[Matthew P]

12 hours ago, 47U said:

The factory has replacement yoke shafts in stock (as a few weeks ago) which retires the 500 hr NDI yoke AD… call around to a few of your favorite MSCs for the best pricing.  The difference in the tubing wall thickness between the old and new shafts is significant.  Plus, it’s about 1.5” longer than the old yoke shaft giving you more clearance to the panel should extreme maneuvers be required (like inadvertent spin recovery).  With my left-side panel upgrade, I lost some of that clearance.  And, you can tighten that set screw down to the standard torque value without worry.  

Do you have a part number

[47U]

2 hours ago, Matthew P said:

Do you have a part number

The ‘66E IPC shows pn 720005-1 for the left yoke shaft and pn 720005-2 for the right yoke shaft.

SB M20-205B updates those to pn 710072-501 left side and pn 710072-502 right side.

[Ragsf15e]

1 hour ago, 47U said:

The ‘66E IPC shows pn 720005-1 for the left yoke shaft and pn 720005-2 for the right yoke shaft.

SB M20-205B updates those to pn 710072-501 left side and pn 710072-502 right side.

Im curious about the new shafts… are they the only thing that gets replaced or are there other various pieces behind the panel that enable them to fit?

[47U]

20 minutes ago, Ragsf15e said:

Im curious about the new shafts… are they the only thing that gets replaced or are there other various pieces behind the panel that enable them to fit?

I replaced the AN attaching hardware on the forward end.  Two AN3 bolts/nuts/washers per side.  My yoke-end of the shaft is not the tapered pin, it’s an AN3 bolt, which made the yoke install pretty easy.  And then went an extra step that was probably overkill.  I don’t think the juice was worth the squeeze.

I also had (previously) procured the two phenolic balls in the panel, thinking that after 60 years they would be worn.  The ball housing halves needs to be shimmed apart with washers to provide clearance to allow the ball to rotate.  It doesn’t move much, but it does move.  That really was the hardest part of the job as the housing is installed from the back of the panel.  The front housing half goes on the three mount screws installed from the front of the panel.  Then the washer shims on each screw (two or three ‘L’ washers is what I used) and then the ball, then the back half of the housing.  Lying on your back, underneath the panel, where your shoulders don’t fit.  Good Mooney times.  The phenolic balls are lubricated with graphite powder, so I bought a can of dry graphite spray and pre-lubed them.  

After all that, the left side yoke shaft feels like it has a nice tight fit without any binding.  The right side feels like it did before I replaced the phenolic ball.  Oh well…

[N204TA]

1 hour ago, Ragsf15e said:

Im curious about the new shafts… are they the only thing that gets replaced or are there other various pieces behind the panel that enable them to fit?

If you keep the original control wheels, you only need to replace the shafts.  If you want to convert to the 201-style control wheels, there are other linkages that need to be swapped.  As 47U said above, you can change the balls in the panel but, if they are in good shape, you’ll don’t have to.  
 

My biggest challenge was all of the wires and the vacuum line that run to the pilot’s control wheel.  As you can see below, the bell crank was welded onto the old tube while the new one is fitted with a sleeve and crossing rivets.  That seriously limits the space to feed things into the tube.  I was able to get the PC cutoff tube and the wires for the post light above the clock into the tube and into the center of the control wheel but I needed to route the PTT and electric trim wires around the shaft and under the panel.