Ram Horn Yokes on Older Cessna 172

[Cessna 180]

I'm looking to replace the older style yokes on a Cessna 172 with the "newer" style ram horn yokes. I've heard of guys in the US having these changed out under field approval. Is this a realistic avenue in Canada, assuming factory yokes, tagged, from a retired Skyhawk? What sort of paperwork exercise would you have to go through or could this be a logbook entry from an AME?

Thanks!

[Big Pistons Forever]

One issue is the old style square yolks were attached at the top of the square with the side part you hold on to below the shaft. The newer style attach at the bottom with the handles above the attach point.

Putting a newer style yolk on the old style panel will have the handles uncomfortably high

[PilotDAR]

Although it may seem like an easy thing to change, the prevailing regulations require that the "data" be available, appropriate to the intended change. If the data exists (parts catalog say it's eligible, or there's an STC) you're good to use that data. In the absence of such data, creating it is possible, but silly expensive in proportion to such a simple mod. In Canada, there is no "simple" way to approve such a change. Some people bring to mind the FAA "337 form" way of doing things. It's a potentially incomplete way of creating "data" and therefore not an accepted way of doing things in Canada.

Just for your reference, in the present Canadian system, a serialized STC is possible for this very simple change. However, even the most simple sSTC has a $220 fee to TC, and takes at least 4 hours of my time to issue - for the most simple change.

For your self education, review AWM 571.06, and then Appendix A to that standard:

https://tc.canada.ca/en/corporate-servi ... ntenance-0

https://tc.canada.ca/en/corporate-servi ... ns-repairs

As you find for yourself that this really would not rise to the level of being "major", and as such could be handled with other "data", you'll still find that that data is not there either (AC43.13 does not describe this change). I can say that some forward thinking people at TC were trying to create new simplified ways of doing exactly this type of change, but there was just no inertia to get the ball rolling - and TC effort to do it. It is this type of regulatory simplification what a group like COPA should take on. I discussed it with COPA management years ago, but again, lack of momentum.

[boeingboy]

I'm assuming these were installed by Cessna when that later model Skyhawk was built....if that's the case it's as simple as installing them and using the IPC and the service manual for that model year as your data.

One issue is the old style square yolks were attached at the top of the square with the side part you hold on to below the shaft. The newer style attach at the bottom with the handles above the attach point.

Not really - they were all the same yokes and mounting locations. Some have just inverted them. Yes some were like that from the factory - but again...same mount just inverted.

[groncher]

You can't just use the IPC from a different model as data. The part being installed has to be effective to the model you're installing it on.

[Cessna 180]

Thanks for the replys. Seems like there is an STCd aftermarket replacement, but we'll likely skip this mod for now.

Thanks again!

[boeingboy]

You can't just use the IPC from a different model as data.

Actually - yes you can. I've done it numerous times. Not only with the IPC/service manual but with structural repairs as well. TC has signed off on it every time.

[CFR]

http://www.avion.com/CessnaControWheels ... heels.html