Has anyone on here gotten a field approval to run a McCauley C203 on a O-470-50 engine?

The C58 and C66 are field approved, but not the C203, for some reason.

Have you called Steve? He could probably steer you towards any hopefuls. I have heard of it being done, but have never found that golden unicorn. I have also heard (from Steve) that the 203/4 would not pass a vibration analysis, which is why they couldn't get them on the STC.

FWIW, lots of people poo-poo the decades old, obsolete design of the C58/66 props.... which pretty much sums up the design of the airplane we're contemplating hanging them on. I have on numerous occasions run a 'state of the art' composite prop neck and neck with the 'obsolete' C66 on like model airframes with like built O-470/50's.... I have switched airplanes with offending pilots, just to rule out technique ... If money IS a part of the equation the obsolete prop wins the deal every time.... you simply can't make the few (literally) feet or mph or pounds pencil out.... If you are looking at a C203/4 and can't get it done, I'd consider FA'ing a C66 (I think brother Gary still has one for sale) and never look back...

Take care, Rob

BTW.... I own examples of both

North Sound Aviation holds STC SA388NW which approves use of an 82" or 88" C201 or C203 prop on the Cessna 180 - 180F,
using the 470K & 470L engines.
It's my understanding that the O-470K & L engines have the same crankshaft configuration
(four 4th order dampers) as required for the 470-50 Ponk engine.
The 470-50 is not a K or L, but since the crank configuration is the same a field approval based on this STC may be possible.
Jim Hayton owns North Sound Aviation, he's located in Sedro Wooley, WA.

Thanks for the valuable feedback Rob and Hotrod.

I had an impulse coupling come apart in a mag, which filled my 750 hour 470R up with chips.

My family and I fly in the plane over a lot of terrain where a forced landing would be questionably survivable, so I will be having it taken down and overhauled. It seems like Ponking it is a good idea, but doing that in addition to a new prop is stretching my budget a little thin, so I'm looking pretty hard at trying to use my nice, newish C203.

The C66 would work for sure, but I am a big fan of "the known quantity" AKA - my C203 that I've been running since new.

Eventually, in a year or three, I will most likely get an MT, but looking for an interim solution while my finances stabilize after this unexpected hit.

Rob - is Brother Gary "Shortfielder"? If so, he sold his C66.

Hotrod - Thanks for the info on that STC. That may really help to substantiate the F.A.

hotrod180 wrote:North Sound Aviation holds STC SA388NW which approves use of an 82" or 88" C201 or C203 prop on the Cessna 180 - 180F,
using the 470K & 470L engines.
It's my understanding that the O-470K & L engines have the same crankshaft configuration
(four 4th order dampers) as required for the 470-50 Ponk engine.
The 470-50 is not a K or L, but since the crank configuration is the same a field approval based on this STC may be possible.
Jim Hayton owns North Sound Aviation, he's located in Sedro Wooley, WA.

That is great information. My Pponk is built from a K model, so even more so for me.
FWIW, I am not opposed to the more modern hub style, I just have a known performance base on the C66 and an existing FA on my aircraft, and it compares very favorably to the MT normally on my plane. I'd sure like to try a 203 sometime for comparison.

Take care, Rob

Scolopax wrote:Has anyone on here gotten a field approval to run a McCauley C203 on a O-470-50 engine?

The C58 and C66 are field approved, but not the C203, for some reason.

I didn’t get any joy from Steve or anyone else when I was asking this question a few years ago. Thus, had to sell my beautiful C203 and buy a new 3-blade prop. Sorry to hear about the impulse coupling problem. Let me know if I can help out.


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I decided to get in to a freshly overhauled C66.

Should be a good and legal solution.