Prop touch-up

OkieFlyer

OkieFlyer

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Andrew L.
The paint on the pilot side (face?) of my McCauley two-blade constant speed prop is in bad shape. In fact, I'd say there is less paint than aluminum showing. I've always been good about keeping the prop clean and wiping it occasionally with CorrosionX, so there isn't any corrosion that I can see.

I'm planning on giving it a light sand with 400 grit, a shot of appropriate primer (zinc chromate or self-etching?), and finishing with some flat black Rustoleum.

The front facing side (blade back?) is in pretty good shape, but I may go ahead and gently scuff and shoot a little semi-gloss Rustoleum.

Any reason I can't do this? I've gone through a couple extremely convoluted threads on the subject, and came away with no good reason I can't do it as an owner. Correct me if I'm wrong.
 
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Skip the primer and go directly with the flat black + primer, on the front side use satin instead of semi-gloss. Someone will be along shortly to tell you that you can't do it because you'll crash into a busload of nuns on their way to penguin petting.
 
Timbeck2 said:
Skip the primer and go directly with the flat black + primer, on the front side use satin instead of semi-gloss. Someone will be along shortly to tell you that you can't do it because you'll crash into a busload of nuns on their way to penguin petting.
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ill throw it out for the popcorn fest.....

here are the areas in 43 appendix a that apply.

(9) Refinishing decorative coating of fuselage, balloon baskets, wings tail group surfaces (excluding balanced control surfaces), fairings, cowlings, landing gear, cabin, or cockpit interior when removal or disassembly of any primary structure or operating system is not required.

propellers are not in that list, so that does not cover it. now heres where you can get creative.

(10) Applying preservative or protective material to components where no disassembly of any primary structure or operating system is involved and where such coating is not prohibited or is not contrary to good practices.

doesn't the propeller manufacturer require a protective coating on the prop? just ask hartzell about polishing one of their props. so wouldn't that qualify as a preservative or protective material?

to make it muddier, most propeller manufactures list what paints must be used on their props in the manuals. however, as I have stated before in these ****ing matches those manuals are no longer "FAA APPROVED" and the sections calling it out are not the continuing airworthy section. so I say it will not make it unairworthy to use krylon or what ever, some do not agree and hartzell flat out refused to answer the question when i asked them. I guess only the FAA could answer that.

bottom line, talk to your IA before you do it, most IA's I know have no problem with it.

bob
 
Why not strip and polish the whole thing ?
 
Tom-D said:
Why not strip and polish the whole thing ?
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Do you mean leave it polished? If so, because I don't want a polished propeller.

If you mean strip it and repaint the whole thing, the answer is because I intend to get a mid-life inspection done on it at some point. Therefore, I don't want to put that much effort into something that will get stripped before long.
 
Tom-D said:
Show me the enforceable FAR that requires the coatings to stay in place during service?
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But that's not what we're talking about, now is it Tom?

There's a big difference between a bit paint eroding off because of flying thru rainstorms and purposely removing ALL the paint.

But you just keep on playing your games. We all enjoy them so much.
 
Gentlemen, I don't give two chits about whether polishing is acceptable. I have no desire to polish mine, and there is no need to even entertain starting a peepee match about it.

The questions I have are:
1) Do you or don't you agree that it's okay for me (owner, not A/P) to touch up the paint, provided I do not move any metal, and not significantly affect the balance?
2) What primer is appropriate for the face that has a significant amount of exposed aluminum before top coating?
3) Do you have any other relevant tips or advice to help me accomplish this task?


P.S. I will not be attempting to use Tempo. If I do it, it's going to be rattle can Rustoleum or the like.
 
OkieFlyer said:
Gentlemen, I don't give two chits about whether polishing is acceptable. I have no desire to polish mine,
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I don't blame for a minute, they are a hell of a job to keep looking nice.
and a lot of work to polish.
 
So do you strip first or polish first? When does buffing come in?
 
OkieFlyer said:
Any reason I can't do this? I
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No there isn't any rule saying you can't, but is it a good idea? I my opinion if you are going to have a mid life inspection done,(what ever that is) why not simply have it IRANed? That way it will get stripped and inspected by some one who knows what they are doing, and repainted and re-balanced, and returned to service like new.
I would never sand on a prop blade, it isn't what you should be doing.
Any cleaning that must be done should only be scrubbed with a soft bristle brush and "alum-prep"
If you must re-coat the back side simply wash it and add a layer of flat black.

And like it or not, that's my opinion.
 
OkieFlyer said:
The questions I have are:
1) Do you or don't you agree that it's okay for me (owner, not A/P) to touch up the paint, provided I do not move any metal, and not significantly affect the balance? I agree it's okay for you to touch up the paint with your cautions/concerns noted.
2) What primer is appropriate for the face that has a significant amount of exposed aluminum before top coating? I dun tole ya, skip the fancy aluminum primer and buy the paint + primer (matter of fact, it states it just like that on the Rustoleum can) and spray to your heart's content.
3) Do you have any other relevant tips or advice to help me accomplish this task? Removing the prop makes this job easier but if you don't want to go that route, make sure you mask well. Another tip: The flat black on the back side of the prop will NOT look all pretty and uniform after you paint. Don't worry, use a burgundy scotch brite pad and with a light touch, smooth it out; its flat paint and will NOT be damaged. On the front side, use satin and take your time with multiple THIN coats. You can even buy new McCaully/Sensenich, etc. stickers from Spruce to finish it off.


P.S. I will not be attempting to use Tempo. If I do it, it's going to be rattle can Rustoleum or the like.
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Tom-D said:
No there isn't any rule saying you can't, but is it a good idea? I my opinion if you are going to have a mid life inspection done,(what ever that is) why not simply have it IRANed? That way it will get stripped and inspected by some one who knows what they are doing, and repainted and re-balanced, and returned to service like new.
I would never sand on a prop blade, it isn't what you should be doing.
Any cleaning that must be done should only be scrubbed with a soft bristle brush and "alum-prep"
If you must re-coat the back side simply wash it and add a layer of flat black.

And like it or not, that's my opinion.
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I have no problem with your opinion. That's exactly what I wanted. Thank you for it.

I've seen the "midlife inspection" written about in at least a couple of places on the interweb. Figured it was a normal thing. The prop shop nearest me says they disassemble the prop, clean everything, visually inspect for corrosion and cracks, dress and paint the blades, reassemble with new seals, set angles, and static balance. Frankly, that's more than I need at this time. I really just need the dings dressed and paint it. Do most A&Ps do that? I asked mine about it, and he apparently doesn't like to do so. I don't know what and IRAN means. Forgive me, I'm not hip to all the lingo.

One question though. With all the chipped paint, do I not want to smooth out the surface? Seems counter-intuitive to paint over a rough, unprepared surface. I'm talking fine paper here, for smoothing the jagged edges of the chipped paint, not removing any aluminum.


I heard ya @Timbeck2 . Wasn't 100% sure if you were serious about the all in one paint and primer stuff. Got it now.
I can't remove the prop without and A&P, right? We don't have those here. Didn't really want to fly it somewhere to remove the prop just to paint it.
 
On some props in some occasions the last coat of paint is the final balance. I don't know which prop we are talking about nor would I like to guess. So do you really want to sand some off?

Simply treat bare metal with alodine, paint a light coat right over it and try to get the same amount on each blade.

your blades have protection coated on them, (anodizing) they will be OK until the next repair cycle.
Anodizing.. look it up.
 
now that you have looked it up do you really want to sand on your prop?

search
 
This should be fun!

http://mccauley.txtav.com/-/media/m...hash=7F613FABB08554A85D2AB8E61549614D09B0F362

The link is to the McCauley Owner/Operator Manual. Starting at about page 700 is how McCauley wants you to touch up the paint on their prop.

Basically, alodine any bare spots and coat using appropriate paint. I would rough up the face to try to feather the paint in, but don't go nuts. Do not strip, the idea is to restore the protective treatment as needed, not to completely refinish the prop.

I do believe the regs allow for this as mentioned previously.

I actually like the Tempo prop epoxy paint. My procedure is to shake it well, place in a warm place (not hot) for 20-30 minutes to warm the contents, shake again and spray. If it isn't warmed up, it will spit and clog the nozzle. It does seem to last pretty well as long as you can get it spraying properly. But any paint is better than none at all!

PS Look for any nicks that should be dealt with now, before painting. Dressing would be best left to a mechanic.
 
JAWS said:
I do believe the regs allow for this as mentioned previously.
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Not in the US, FAR 43-A preventive maintenance does no add prop painting in the 31 items allowed by owners.

I never did see a page 700 in your link.
 
For those of you who would like to know what the FAA's thoughts on propeller maintenance is : read AC 20-37E
https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_20-37e.pdf
quote
a. Sources of Propeller Repair Information. Airworthiness Directives (AD), type certificate (TC) data sheets, manufacturers’ manuals, service letters, and bulletins specify methods and limits for propeller maintenance, inspection, repair, and removal from service. When a manufacturer’s data specifies that major repairs are permitted to a specific model blade or other propeller component, only an appropriately rated repair facility may accomplish those repairs. An FAA-certificated mechanic with at least a powerplant rating can accomplish all other propeller maintenance and minor repair by using the practices and techniques specified by this advisory circular (AC) and in the propeller manufacturer’s service data. Some maintenance and minor repairs in this category are the removal of minor nicks, scratches, small areas of surface corrosion, painting, and minor deicer boot repairs. Because of the complexity of propeller damage and because damage tends to be hidden or not obvious to untrained maintenance personnel, we recommend that propeller damage be referred to experienced repair personnel whenever doubt exists regarding a condition that has been observed. We further recommend that owners/operators follow the manufacturer’s maintenance and overhaul program.
end quote
Now consider, that an A&P will not have the tools and equipment & data to comply with 43.13
how many A&Ps have a full library of prop maintenance manuals?
 
What I think will be nearly comical is this, the OP has stated that he has wiped the prop with Corrosion X, How many believe he can get paint to stick with out a total strip and etch?
 
The manual link that I posted above came directly from the McCauley website. It provides the ICA's to keep most McCauley props airworthy.

The AC above is guidance only, not regulatory. "Someone" around here often states something to the effect of "show me the regulation that prevents me from ...". The reg already quoted above would do nicely here (FAR 43, appendix A I believe)!

unsafervguy said:
(10) Applying preservative or protective material to components where no disassembly of any primary structure or operating system is involved and where such coating is not prohibited or is not contrary to good practices.
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On a spam can, have at at! If any questions, contact your local aircraft mechanic. Don't rely on POA!
 
IRAN = Inspect and Repair As Necessary.

When it comes to props, many say to NEVER overhaul, only IRAN. (IIRC) Overhaul involves MANDATORY filing down the prop and losing significant amounts material. When the engine in my plane was overhauled, I had the prop IRAN'ed, not overhauled.
 
OkieFlyer said:
Any reason I can't do this? I've gone through a couple extremely convoluted threads on the subject, and came away with no good reason I can't do it as an owner. Correct me if I'm wrong.
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Provided it is only paint touch it will fall under preventative maintenance/protective coating application. Logbook entry with reference and sign off. This "convoluted" thread has several reference links:
https://www.pilotsofamerica.com/community/threads/propeller-paint.105749/page-2#post-2379426
 
For the love of Pete, don't show the prop to an A&P! You'll find yourself in some pretty deep kimchi! Ask me how I know!

And Okie, she's Baaaack! Wanna go flying??
 
Tom-D said:
What I think will be nearly comical is this, the OP has stated that he has wiped the prop with Corrosion X, How many believe he can get paint to stick with out a total strip and etch?
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Raises hand. Corrosion X is in mineral oil when you buy it. Anything that hasn't polymerized will come off the propeller with turpentine. Anything that has polymerized and remained on the prop after cleaning with turpentine will hold paint.
 
I gotta second the don't sand thing. Sandpaper has metal that can become embedded in the aluminum and initiate similar metal corrosion. I would probably leave the whole thing to a mechanic, since there could be other gotchas beyond my experience.

I'm reminded of a house near me that's been under construction by the owner since I moved here. He just started with one project and kept going, a real do it yourselfer. His house has been condemned by the authorities because none of what he did met local building codes.
 
Small chance the prop may go out of balance from the paint. BTW, its possible to BALANCE a prop using paint (paint the blade that needs the weight).
 
I am looking at a plane now that currently has a polished prop that appears to be in great shape. If I end up buying it my thought is if I can find an IA that will pass it as is I will leave it. If not break out the rattle can and have at it. Probably could even get an A&P or two to sign off on it if I really needed to but I am not sure you do.
 
steingar said:
I gotta second the don't sand thing. Sandpaper has metal that can become embedded in the aluminum and initiate similar metal corrosion. I would probably leave the whole thing to a mechanic, since there could be other gotchas beyond my experience.

I'm reminded of a house near me that's been under construction by the owner since I moved here. He just started with one project and kept going, a real do it yourselfer. His house has been condemned by the authorities because none of what he did met local building codes.
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well....you certainly wouldn't want to go sand blasting it.o_O
 
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