What propeller should I use

:roll: I have a backcountry Pa-12 . I just purchased a 0-360 and dont know what prop to buy. I was told that the 84-42 pawnee prop would mostly be my best choice. I fly only on floats. Does any one out there
have the proper number for that prop is it a 1p235 pfa or afa.

The 1P235 is only approved on a Pawnee, unless you are exp. I have a 1P235 8443 on a 180hp+ Smith Cub. I love it.

Lou

I am also exp Pa-12 from Turbine cubs. Is your prop an pfa or afa and where can I find one.

prop

it sould be a IP-235-AFA 84-whatever pitch you want. It is known in Ag circles as the toothpick prop for the 235 hp Pawnee and was pitchd at 52 on them.

Dave

They are a great prop and some say they will chew there way though lots of wires and just keep going...........

Try Mike Baird at Tiffin Aire.They are the largest fixed pitch dealer in the country and have been real good on pricing and service.

Bill

The following is from the type certificate data sheet for the 1P-235 propeller. You will note that when used on the 0-360 that there is a maximum diameter limit of 78" for vibration considerations. I know that you are experimental but don't you think that maybe McCauley has the 78" limit for a reason? I am sure that the prop does give the desired performance but I for one would not wish to risk my life to the possibility of structural damage to either the engine or the prop by using this combination. The 1A-200 propeller is approved vibration wise in the larger diameters, up to 82", which we desire for our Cubs with 0-360s.
Penn Yan's STC uses the 1A-200 82"dia.

I would not want to run the risk of having a piece of prop come off. Unless McCauley would tell us it is safe to run over 78" I would choose another prop.

TYPE CERTIFICATE DATA SHEET NO. P12EA

--------------------------------------------------------------------------------
NOTE 9.
Table of Propeller-Engine Combinations Approved
Vibrationwise for Use on Normal Category Single Engine Tractor Aircraft

The maximum and minimum propeller diameters that can be used from a vibration
standpoint are shown below. No reduction below the minimum diameter listed is
permissible since this figure includes the diameter reduction allowable for
repair purposes.

Max. Dia. Min. Dia.
Propeller (Inches) (Inches) Placards
Model Engine Model
1P235/AFA Lycoming O-540 &IO-540 series, with one 5th and one-6th 84 77 None
order crankshaft damper configuration (up to 260 hp @2700 rpm)

1P235/PFA Lycoming O-360 series (up to 180 hp @2700 rpm) 78 74 None

1B235/BFA Lycoming IO-360 series (up to 200 hp @2700 rpm) 78 74 None


This did not cut and paste very well. I hope that you can understand it.

FdxLou said:

The 1P235 is only approved on a Pawnee, unless you are exp. I have a 1P235 8443 on a 180hp+ Smith Cub. I love it.

Lou

Click to expand...

Same for me.

prop

As far a vibrations I know several 235 props that have been run on 360 & 320 engines for thousands of hours without failure. They are very snooth like a borer prop and other than being 2" longer and about 1/4 to 1/2 more cord mid blade they look alike. Maybe McCauley just didn't do Vibration tests on the 4 cylinder lycomings and are in CYA mode.

The 200 prop is a big fat thing and alot is around 10 lbs more on the nose.

dave

dave ,
what has too be done to run it on a 0-320 exp.

jr.

JR you can run the Pawnee 1P235 on an O320 by changing the prop bolt bushings in the crank flange to accept the bigger bolts. Or machine bushings to fit the prop hub so the standard O320 bolts will go thru them. You will have to go to the spinner for a 180 Hp. Try a 84-40 on a hopped up O320

RA, What you were told first is right. O-360 on floats = 1P235 8442

1P235 8443 on floats = just say no. (it was GREAT on wheels. But with floats and the Cub loaded with gas and "stuff" - then not so much. :-?

The problem with these kinds of questions on props is that you don't know why the manufacturer didn't approve them on those engines at those lengths.

On the C-170 with AvCon 180 hp, a lot of guys were running the CS prop off the Pawnees--the Hartzell HC 2YK 84xx on their O-360s. Nobody had problems that I'm aware of.

At some point, a mechanic who was tired of seeing these on airplanes people wanted him to sign off for inspections got in touch with Hartzell, and explained to them that there were a number of people out there running that prop/engine combination.

Hartzell did a vibration survey of the combination, and found a 3rd or 4th order (as in not detectable by human butts...) destructive harmonic somewhere around 2600 to 2700 rpm. Takeoff rpm.

Hartzell then recommended sawing a couple inches off those props to 80 inch diameter and installation of a harmonic damper, which passed vibration analysis.

It may well be that McCauley simply hasn't tested this prop/engine combination at the longer lengths. Or it may be that they did and found a destructive harmonic.

I'm with Skywagon on this one: Prop/engine vibration issues is NOT something I'd mess with. Just because you don't FEEL vibration, and just because somebody else has been using one for a while doesn't mean yours won't fail.

And, if the prop fails...things are GOING to be ugly.

MTV

Charlie Centers STC for the 0360 calls for a McCauley 1A200/DFA 82-45. I have a friend with this on his PA-14 for several hundred hours now and he has no complaints.