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STC for Pre-J Mooney Yokes


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Hey Everyone,

I am considering going after a STC for Pre-J yokes in partner with a friend of mine. Most certainly we would undercut the pricing for any other yokes on the market. After searching extensively for yokes for my M20E which would accommodate a PTT, trim switch, AP cutoff, etc., I just can't seem to find any or any which are reasonable and just bold on. I am trying to gauge interest and any insight on the process for obtaining a STC. I also just considered fabricating a pilot/owner part and having it field approved but then figured I may be able to help others.

I am also going to make the release levers for the rear seats out of aluminum if anyone is interested in a set. Going to pull mine out today as I will see my partner tomorrow. Not sure of the cost as yet but when they are made, I will post a pic here.

Let me know what you think and if it is worth the effort.

Bob

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Yokes, as simple as they sound... come with plenty of baggage.

Anything connected with flight controls starts to become extra complicated.

  • Cracked or broken can cause a loss of control...
  • oxidation can initiation cracks or breaks...
  • Choices of materials and coatings are challenges in Mooney’s past...

An STC would have to cover all kinds of unexpected costs related to proving no harm comes from the new design and parts...

When a plane is designed all the new parts get flight tested all at once... making things easier, less expensive, to flight test at the same time...

 

Thinking inside the box...

  • Any dimensional changes would need to be tested to prove no issues arise in flight, with various dimensions of pilots behind the yoke.
  • any weight and dimension changes would have an effect on control flutter characteristics... more testing...
  • MS has a few STC writers and parts / system builders... on board.
  • Depending how close the new yoke is to a previous yoke, you might be able to come up with a user supplied part...

How much experience and what type of experience do you have to bring to this project?

Carbon fiber yokes could make an excellent opportunity to make a weighty improvement...

 

See if you can tell what improvements have been made in the Ultras... and in the experimental world...?

PP thoughts only, make it happen!

 Best regards,

-a-

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The idea would be for the control yokes to fit the original 3/4" shafts and look as close as possible to my original 68 M20E control yokes but (possibly) a bit larger in circumference to accommodate the the hollowed center for wiring. I would like to try an keep the same weight and balancing if possible. I may or may not incorporate the old PC system. I know my PC still works but I am not sure how many out there still do.

My friend is a design engineer for a company doing all sorts of work for automotive, aerospace, etc. They have all the necessary equipment to make the parts. I certainly can appreciate the user supplied part idea as the paperwork and headaches are no doubt much less. I am certainly in the infant stages of the process and gathering information. Please send any other thoughts, ideas, brain farts, etc.

Bob

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It's worth noting that the vintage planes have a 500hr recurring AD from 1978 to remove the yokes and inspect the aft portion of the control shafts for cracks:

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/AOCADSearch/9D64BD7BF95E495B86256A3B007021F5?OpenDocument

Someone poor bastard might have had a yoke snap off one of these thinner shafts in flight at some point.  So retrofitting newer style yokes onto the old shafts in most vintage planes may be problematic for safety reasons as well as the regulatory ones @carusoam cites.

The factory has previously sold a retrofit kit for the newer yokes on heavier shafts: PN940021507/940021-507, which clears the AD.  Someone previously installed this kit on my plane.  Duplicating that entire kit as a PMA'd part might be the easiest way to go?  

 

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I would be interested in newer style yokes on my F,  with room for PC system valve and PTT on left side of yoke and perhaps additional switch (IDENT)  on RHS horn.

I see no reason to keep the shape of the old yokes as those are available and inexpensive (used) and (to me) not desirable due to lack of PTT. YMMV.

Regards,

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One thing to keep in mind is that the STC is only design approval.  You will need to set up a PMA to manufacture the parts that would then be installed per your STC.  In my experience, getting the PMA is as time consuming as the STC, and then you have to maintain it, including annual visits to the factory by the FAA.  There are partnering opportunities on the PMA, but that should be considered up front, to optimize the STC for the situation.  Happy to talk to you about my experiences with both if you move forward on it. 

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20 hours ago, Glenn said:

I used Cygnet yokes when I redid the panel on my '67F. https://www.cygnet-aero.com/control-wheel-ca60-524080-17 They have an adapter for either the large or the small shaft.

012.JPG

IMG_0577.JPG

Looks like this company made a direct copy of the Beechcraft control wheels to avoid any regulatory hassles for install on those aircraft - it is a precise copy of the original part, and they are able to offer at a reasonable sounding price. There's probably a place in the market to do the same for the same for the J-model and later style wheels for vintage aircraft. As previously mentioned, Mooney has previously offered a kit to upgrade the vintage wheels and shafts and eliminate the AD on them - there's probably a place in the market for a copy of that kit....

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