The experimental I am looking at buying has a McCauley CS prop off a 182 on it, I don't know the model for sure but I think it is a C66. When I flew the plane last week I was disappointed with the performance and have been doing some looking to figure out why. Think I may have it figured out; on takeoff it is only turning ~2400 rpm and redline is 2700rpm. I'm going to call the engine builder on Tuesday to verify that I should be seeing close to 2700 with the prop all the way in. That extra 300rpm should make a big difference, at least I hope it does.

So my question, how do you adjust the fine pitch limit? The owner said he thought it was done with washers; pull the spinner, remove a lock-ring and add the number of required washers. Anyone have a copy of the service manual for a C66 that would be willing to help us out. Hoping to make the adjustment and fly the plane again soon.

Engine is a Lyc. O-360. I was seeing 22" WOT at DA of about 8K.

On a converted 175 I used to fly for my instrment work, the mechanic played with the prop stop to get rated redline for the local field on takeoff. To his dismay, the PITA adjustment had zero effect. He then simply removed the cowling and made a quick adjustment on the governor...apparently there is a hi rpm stop screw there as well. After spending 3 hours trying to adjust the prop, he had the redline set with the governor and the cowl back on in about 45 minutes. So the prop stop might not be the gating factor. Im not sure exactly what he did, but he apparently fixed it on the governor.

Whee

A C66 prop is for a Continental engine, so you must have something else.

Mac prop rpm is controlled by adjusting the governor.

The following is from the McCauley website.

General Calibration Procedures
Following Installation of McCauley Constant Speed Governors

A. Perform Static Run-up: Lock aircraft brakes. Place cockpit propeller RPM lever in high RPM (takeoff) position. Advance throttle slowly to maximum permitted engine manifold pressure limits. Record propeller RPM. If local wind conditions are over 5 knots, repeat check with aircraft pointed in opposite direction and average the two numbers. As a general rule, propeller RPM should be 25-100 RPM below redline limit during the above check.

B. Perform Flight Test: During takeoff acceleration, record maximum propeller RPM. When sufficient altitude is reached, level out aircraft, leaving propeller control in full RPM position. Maintain this setting for three (3) to five (5) minutes while monitoring propeller RPM. Following this check, two conditions may exist which require adjustment:

1) If propeller RPM is exceeding redline limit, reduce it to redline using propeller control. Leaving propeller at this redline RPM setting, land aircraft and shutdown. Remove cowling and note position of control arm on governor. Adjust governor high RPM screw clockwise so it just touches stop on governor control arm; this will ensure that the correct arm position for governor redline RPM setting cannot be exceeded.

2) If propeller RPM is below redline limit with max RPM setting on the propeller cockpit control, note RPM and land. Remove engine cowling and adjust the governor high RPM screw counterclockwise to increase RPM.
Note that one full screw turn will cause an increase of approximately 25 RPM.
Perform another test flight to confirm adjustments were sufficient.

General Facts About McCauley Governors

Static Run-Up - What is Normal?

There has been some confusion in the field concerning propeller low blade angle setting, the governor setting and how it relates to static run-up and take-off RPM. As a general rule, engine redline RPM cannot be reached during a full power static run-up. Contrary to popular belief, the governor is not controlling the propeller at this time, the propeller is against its low pitch stop. Attempting to increase propeller static run-up RPM by adjusting the governor high RPM screw will have no effect and will probably result in a propeller overspeed during the take-off roll. On a single engine aircraft several considerations determine both the low and high blade angle settings. Normally 25 to 100 RPM below rated take-off RPM is desirable and acceptable during a static run-up. McCauley's practice is to set the low blade angle so that rated take-off RPM is not reached until the aircraft has reached some significant groundspeed during roll out. At this time, and only this time, the propeller is controlled by the governor. There are two advantages to this practice. First, the maximum static RPM can be used as a check on developed horsepower as with a fixed pitch propeller. Any loss of maximum power over time is readily apparent during a preflight check. Second, if the propeller remains in a flat pitch after take-off due to some malfunction, the higher angle low pitch setting will permit more thrust to be developed to fly the aircraft without overspeeding the engine.


Hope this helps.

flyfish

What lesuther said.

Look at the cable going to the prop governor. With the prop pitch set to fine (knob all the way forward at the panel), the control arm at the governor should be hitting a stop screw. Back this screw out a little* (maybe a full turn to add 300 rpm) and do a full power run up to check the effect. *Note original setting in case you need to go back to it.

Also note that with the prop control full forward, the knob should be about 1/8" shy of hitting the panel so that the knob travel is determined by the stop screw. If this is not the case, the control cable end will need to be adjusted at the governor by extending the cable end to acquire the needed extra length.

bumper

flyfish wrote:A C66 prop is for a Continental engine, so you must have something else.

I guess it probably does then. The owner said the prop was purchased used off a C182 then overhauled and installed on this Lyc. O-360.

flyfish wrote:There has been some confusion in the field concerning propeller low blade angle setting, the governor setting and how it relates to static run-up and take-off RPM. As a general rule, engine redline RPM cannot be reached during a full power static run-up. Contrary to popular belief, the governor is not controlling the propeller at this time, the propeller is against its low pitch stop. Attempting to increase propeller static run-up RPM by adjusting the governor high RPM screw will have no effect and will probably result in a propeller overspeed during the take-off roll. On a single engine aircraft several considerations determine both the low and high blade angle settings. Normally 25 to 100 RPM below rated take-off RPM is desirable and acceptable during a static run-up. McCauley's practice is to set the low blade angle so that rated take-off RPM is not reached until the aircraft has reached some significant groundspeed during roll out. At this time, and only this time, the propeller is controlled by the governor. There are two advantages to this practice. First, the maximum static RPM can be used as a check on developed horsepower as with a fixed pitch propeller. Any loss of maximum power over time is readily apparent during a preflight check. Second, if the propeller remains in a flat pitch after take-off due to some malfunction, the higher angle low pitch setting will permit more thrust to be developed to fly the aircraft without overspeeding the engine.

This makes me think that I need to adjust the low pitch stop. Static is only around 2350. Would be great if all I had to do was adjust a screw on the governor but if the prop is already against the low pitch stop then adjusting the governor wouldn't do anything, right?

With the prop control full fine does it go past 2350 on the takeoff roll and in flight? That's an easy check to see if it's on the fine pitch stop in the prop. If so the rpm should increase until the governor can control it, but 350 rpm is a lot... As mentioned a C66 prop won't fit a lycoming, totally different flange and method of mounting. Pop the spinner off and get the model, or get it from the logbooks then talk to a prop shop

I'll call the owner and get the model number from him tomorrow. It runs up to about 2425rpm on takeoff and in flight. I want to be prepared to make an adjustment in the prop if we need to. I'm planing to go fly it again this week and want to make the needed adjustments before I fly it again. Don't want to get there unprepared to do what needs to be done to fix the problem.

Hey there whee. Good chance you'll have to have that prop reshimmed. Check that governor and if it's adjusted out all the way then you'll have to take the prop into the prop shop. Since it was probably off of an o-470 its going to be set for more power, which would be a bigger bite at finest pitch. Not having as much power would require less bite allowing your motor to spin up to higher rpm. I ramble a little but hopefully that makes a little sense...

The prop probably came off a 182 rg. (O-540) That would make it a b2d34c214.... As others have said, a c66 won't mate to your crank.
I have seen an O-360 powered Skybolt with this prop, and there are a gazillion money's with the same hub and shorter blades.
I agree with '55, it is likely too much prop to just go right off the 540 onto the 360, it should be relatively painless for the pro shop.

Good luck!


Take care, Rob

That makes sense. I'll check the governor and go from there.

So the rest of the story is the owner bought the prop used and sent it off for overhaul and to be set to run right on a O-360. Two prop strikes/rebuilds later the current blades are shorter, shop didn't tell him they were installing shorter blades, 78" instead of 82". Who knows where they set the low pitch limiter. The shop didn't yellow tag it after the first overhaul because it was an experimental and no other prop shop would touch it on the next overhaul because it was now an experimental prop. The owner called every prop shop in the neighboring states and every one of them said not going to touch it. Guess I have to figure out if it is worth messing with this one or if I should just start over with a yellow tagged one with the longer blades that I want.

Just keep cutting inches off then till you get your rpms..

55wagon wrote:Just keep cutting inches off then till you get your rpms..

Now that reminds me of this one time we had an old fixed pitch Cherokee 6-260.. The prop was like a toothpick and would never go through an overhaul soooo...... Prop + hacksaw = more rpm and a Cherokee 6-260 that made lots of noise but didn't go any better than before

Sorry, off topic!

55wagon wrote:Just keep cutting inches off then till you get your rpms..

haha...right. I was pretty disappointed when I got out the tape measure and only measured 78". Talked to the engine builder about this issue and he said 78" will ok and to set the static rpm at 2700 and allow it to turn up to 2800 on takeoff. Now I just need to identify the prop for sure and get to procedure of adjusting it. He said there was no need to send it to a prop shop, it was a easy thing to do.

Anybody have the manual for a C214 (I'm assuming that is what it is and should know for sure tomorrow) that would be willing to hook me up with the steps I need?

It is a C214 off a 182rg. Got the procedure for changing the low pitch stop. Don't know what happened but I went out there this week and static rpm was ok. Plane flew great and performed well. At least now I know how to adjust the prop and governor.

Thanks everyone.

Whee - I know this is after the fact, but for future referece we also have the McCauley 2 blade CS, a similarly obscure model to yours (C235) of the Cessna 182S / 182RG. That created all sorts of headaches on it's own... be thankful your plane is finished...
The manuals that come with the prop are pretty light. I think you'll learn more from guys who know the game already.


Glad to see you got it all figured out. Adjusting the throttle/prop/mixture/etc controls is typically easy to do, especially if you install it during the build phase and already know how it works. Grab all the knowledge you can off the builder, as it'll serve you well in future.

If it was making 2400 one day and 2700 the next and you didn't change anything, I would not be happy about that. I would be quite uneasy.... There is possibly some problem in the system.

Talking blade length, everyone seems to think 84-86" is about the sweet spot for STOL on that model, but the designer will advocate 82" for comfort and noise balanced with performance...

I hear what you are saying Battson. I'm not real happy about what is going on with the rpm but at this point I am chalking it up to improper leaning technique during run-up, I don't lean the Luscombe unless I am cruising above 10K so I have a lack of experience in that area (DA was about 8k). That is the only thing I can think of that may have caused the low rpm because it is fine now.

I wish the prop was longer than 78" but I'm not going to sweat it for a while. Right now I just want to buy the thing and bring it home.

whee wrote:I wish the prop was longer than 78" but I'm not going to sweat it for a while. Right now I just want to buy the thing and bring it home.

Yes - don't sweat it - when the time comes, McCauley are apparently doing composite blades now , that would have to be more cost-effective than changing to an MT. If they come available that'll be my next purchase. Besides, I love their one-piece hub, those split hubs don't fill me with confidence.