McCauley MCM 6950 Prop on C-85

[jepropst]

Does anyone have a field approval for installing a McCauley MCM 6950 propeller on a C-85 engine with the O-200 upgrade? The MCM 6950 prop was used on Cessna 150 O-200's. I am seeking suppporting data to obtain a field approval for using this prop on my Champ. This prop is approved for use with the Wagner STC for O-200 conversions on Champs. I have heard that the MCM 6950 performs better than the 1B90 7144 or 7146.

[MikeB]

Hi John,
Can't help you out with the paperwork issue but I can tell you that the MCM 6950 seems to work quite well with the 0200 conversion on my L16. I expect it would be the same for the C85/0200 STC conversions. I see around 2500 + on the take off roll and it will run up to just short of the red line (2750 RPM) in the air. As I have only about 6 hours on the engine I haven't nailed all the figures down. I've been running around 2500 RPM cruise so far which seems to give me somewhere between 90 and 95 MPH. Wouldn't mind lowering that a bit for fuel economy after the engine is broken in. The climb is great (but I'm comparing it to my old 65 so probably no comparasion). One old timer up north of here told me I needed a longer prop but I've been satisfied at this point.

Hope someone chimes in with more data and paperwork for you!

Mike Berg

[shorty]

Does anyone have a field approval for installing a McCauley MCM 6950 propeller on a C-85 engine with the O-200 upgrade? The MCM 6950 prop was used on Cessna 150 O-200's. I am seeking suppporting data to obtain a field approval for using this prop on my Champ. This prop is approved for use with the Wagner STC for O-200 conversions on Champs. I have heard that the MCM 6950 performs better than the 1B90 7144 or 7146.

I'm thinkin' that th' 1A100/MCM prop would be a "bolt on addition" to the O-200.
or the 1A101/DCM for th' C-95 and O-200 but th' length is limited to Max of 69 inches, and min of 67.5, and 67 respectively.
as for pitch, I would think that you would have to check th' static RPM requirements of your TCDS. But a pitch of 50 should be right in the envlope.
Most -200s run a standard pitch of 48.

[teecart]

Wish that would work on my 41 Chief with a C-85! Cant find a 71/44, which is what everyone says I need. Those 150 props are everywhere!

[Paul Agaliotis]

John,
I think that prop would be a little short for a C85. You would spin the engine a little too fast. Take a look at the 1A105 McCauley, not a bad prop for the C85.
Paul

[teecart]

So a 1A105 will fit the c-85 tapered crank? And a 1B90 or 1A 90?

[Paul Agaliotis]

The 1A105 is certified for the C75/85/90 and O200. The 1A90 and 1B90 are older props with the A and B referring to the tip design. Either elliptical or squared, McCauley considers them interchangeable. The 105 and 90 pertain to blade design.
Paul

[teecart]

Thanks, that helps a lot! May have found me a prop!