Troubleshooting Constant Speed Prop Blade Rotational Movement on Ground

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Harold Rutila

Pre-takeoff checklist
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Harold Rutila
I am flying an aircraft with an O-540 and a McCauley prop. The prop has about 200 hours on it, but the engine is nearing TBO. I came across a potential issue with the prop that I have not seen discussed much and am looking for input on whether this is an actual issue.

When checking constant speed props during preflight inspections, I apply gentle twisting pressure at the blade root to see if there is any give. Up until now, I've always found blades to be very tight and have never seen any rotational movement from any models on a preflight inspection. This particular prop, however, has approximately 1/8th inch of rotational give to the point where I asked the owners to have it checked out. The mechanic inspecting the airplane reportedly told them it was normal, but I have my suspicions based on the sheer number of constant speed prop-equipped airplanes I have flown.

Any advice?
 
I've never seen 1/8" but I'm not saying there couldn't be something out there that slops that much on the ground.

Easy way to find out for sure would be to call any prop shop with the model number of the prop. They'd know if it was normal for that one to have any play. Free call. Might as well.

I've seen one move out of all of them. But it wasn't 1/8th of an inch. That's a lot of free play compared to anything I've flown with one. The movement I've seen is more like 1/16 or smaller. Just enough if you have it a back and forth twist pretty hard, you could hear a tiny click from some play in the assembly or gears. Almost imperceptible.
 
I imagine McCauley has their owner's manuals on line. The owner's manual should have the limits published.
 
I can't vouch for Macaulay, but Hartzells move more than that out of the box. It's normal (for them).

What is telling is that if this particular propeller now has more play in the blades than it did before.
 
For that propeller, 1/8" would be excessive for my experiance. But call a prop repair station and inquire from them.
 
What's driving you to do that check? I can understand doing it if you knew what you were looking for... Advice: find more of the same model to compare it to, dig into the prop manuals, or contact McCauley.
 
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This reminds me of when I was a NASCAR official. After the feature race they took the top finishers and ran them across the scales.

The head guy calls down to the guy on the scale "You know how much that is supposed to weigh?"

The guy says no. I tell the head guy to ask him why he's weighing it then. That was immediately the question asked.
 
flyingron said:
This reminds me of when I was a NASCAR official. After the feature race they took the top finishers and ran them across the scales.

The head guy calls down to the guy on the scale "You know how much that is supposed to weigh?"

The guy says no. I tell the head guy to ask him why he's weighing it then. That was immediately the question asked.
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Not even close. In your scenario they document their findings. He had a questionable condition, yet, evidently he flew the aircraft anyway, and still has concerns.
 
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That seems like a good amount of play, I'd dig up a Mx/operators manual, or maybe give them a call and they could point you in the right direction.

For me a big factor would be is this abnormal for YOUR prop, was it only 1/16th before or something.

Also is it in all the blades or just one




GlennAB1 said:
What's driving you to do that check? I can understand doing it if you knew what you were looking for... Advice: find more of the same model to compare it to, dig into the prop manuals, or contact McCauley.
Click to expand...

I do a similar check on props, for me it's to see if anything is changing, even if its within spec, if it all of a sudden went from zero play to having play, I need to know why before I'll PIC the thing. It's like "instruments in the green" uhhh nope, in the green is just the first question, second is are the instruments reading as they normally do for that plane, best to catch things before they end up out of spec no?
 
KRyan said:
As I suspected, the info is in the propeller owner's manual online:
http://www.mccauley.textron.com/mpc26ow.pdf
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I don't remember him giving a prop model number. You sure that's what is on his aircraft?

My suggestion to call a prop shop still stands... because their first question is going to be to get the full model number off of the thing, and probably serial number, and call them back.

Or they're going to couch it with, "IF... your prop is the usual prop on that aircraft with that engine..."
 
They only have two manuals, one for alum blades, the other for composite. the link is for the aluminum blade models.
 
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