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Composite prop wear and tear

P

prkaye

Well Known Member
I bought a 3-blade composite prop from Catto Props for my RV-9A. I've got about 190 hours on the prop now. Doing my inspection recently I took note of the chipping of the material along the leading edges of the blades. I'm attaching a photograph. I'm writing to ask whether this is still within the tolerance of normal wear and tear? Should I do anything to sand the edge of the prop? Should I put any kind of leading-edge protector tape on to prevent further damage?

2ldvvgy.jpg
 
IMHO, That prop is in need of repair before further flight. Excellent picture. Id be interested to hear if Craig feels the same way.
 
Yup, that is what mine looked like after just 1 hour in mist IMC. I used epoxy resin to bond the leading edge and prevent further erosion of the glass on mine but that was only a temporary solution. Also, balance was a concern though I had a 3 blade. That is why I eventually went to another prop. I loved the Catto prop but would not buy another today without the leading edge metal option.
The leading edge tape would prevent that where I could keep the tape adhered - which was all but the rounded tip. After just one flight in significant rain I had to replace the tape. It did work to prevent that though where I had tape on the prop.
 
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This is the very reason that most composite props have the nickel leading edge. You should as Craig about the retrofit availability for your prop.
 
Sensenich wood-core props look the same way after flying through rain. It's just a limitation of the material. I'll buy another Catto prop for my RV-3B when the time comes, with a nickel leading edge. The nickel looks really sharp, too.
 
My Catto has been in back country strips and flown through very light rain with over three hundred hours. Before that I had a Great American wood prop into the same conditions for 22 years. Avoid rain when possible and if not throttle back to 2200 RPM or less. Unless on hard surface runway, using very judicious power application initially while on gravel or dirt will decrease leading edge erosion. Otherwise, going to a metal leading edge would be some benefit, but my recommendation for gravel and dirt remain the same. Oh, did I mention partial flaps to get off the surface sooner?

Cheers,

Hans
 
Ok, thanks guys. Based on your comments about rain, I'm quite certain that's the cause. I have ended up in rain on a couple of occasions. When I do replace the prop, I'll definitely get one with the metal leading edge. I may do that sooner rather than later, but I recall there was a bit of a lead-time on ordering Catto props and I really don't want to be grounded for any length of time this spring.
I've emailed Craig, but I imagine they're off today for Easter. I'll let you all know what he says.
 
That prop is repairable. Craig can give you the details and you can decide if its a task you are comfortable with or if you want to ship it out. (FYI -call Craig as email responses may be slow)

My experience before nickel edges was that I had to throttle back to 1900 RPM and even then I had erosion at the very tips.

Don't sand down what you have. Talk with Craig first. The procedure will be to build up the edge and sand back to the profile. Then coat with a compatible epoxy paint finish.

It's not hard to do but it is a multi-step process.

example: http://thesalmonfarm.org/blog/p/3395
 
I just called and spoke with someone - I think it was Craig's daughter maybe? Anyway, she said they'd take a look at the photo and get back to me today. I told her I'd probably order a new one, but the lead time is 3.5 months, which is way too long to be grounded. I told her if there was an interim repair I could do myself, I'd rather do that than ship it back and forth. She mentioned that JB-Weld is actually something they recommend for those repairs.
I'll post the complete advice once I hear back.
 
Prop damage

I have experience with the Catto on a 0 360 Pitts and the MT on the Sukhoi off a airport that had a lot of loose stones and gravel.
NO RUNUPS- a dead mag check before takeoff, warm up the engine at no more than 1200 rpm. On takeoff EASE THE POWER IN. Minimal power for taxi and check the mags at a low power setting before landing.
I flew the Pitts thru some very heavy rain at 1900 r/m with almost no damage.
The JB weld should work great for repair. I have never used it on a prop but it should work fine. I would allow 24 hours or at least overnight before sanding and recoating.
 
On my old Aymar-Demuth wooden prop, it was claimed to have been constructed with a "metal filled epoxy" leading edge to resist erosion. After I flew home through some rain (at 1900 rpm to help save the prop), it still wore thru the paint enough to reveal the tell-tale familiar gray color of what looked exactly like JB Weld :D

Then when I removed the prop to touch up the paint, I discovered a couple small cracks on the back side of a blade root. Since delivery on a new Catto prop was going to be a long wait, I opted for one of the new ground adjustable carbon fiber Sensenich props with stainless steel leading edges instead. It ended up costing a lot more money than a new prop from Catto but I've been extremely pleased with the smoothness, good looks, and great performance of it. Delivery was immediate too.
 
If I do use the JB weld, I'll have to see what my options are to paint over top of the JB weld so it looks a little better. Not sure if I'd have to buy a special paint for this purpose, or just use any epoxy-based spray paint from the hardware store. I wouldn't paint the whole prop, of course, just something along the very edge to cover up the JB weld to some extent.
 
prkaye said:
If I do use the JB weld, I'll have to see what my options are to paint over top of the JB weld so it looks a little better. Not sure if I'd have to buy a special paint for this purpose, or just use any epoxy-based spray paint from the hardware store. I wouldn't paint the whole prop, of course, just something along the very edge to cover up the JB weld to some extent.
Click to expand...

Consider this:
http://www.marinetex.com/marinetexepoxyputty.html
Comes in white and cures strong.
 
Still need to paint a good portion of it black. Prop is black with white tips. Damage is along the edges spanning both colors.
 
Paint

Randolph green epoxy works very well over JB weld. Second choice is PPG epoxy. I don't use hardware store paint except for guide coat when sanding primer.
 
We are talking about a prop used for flying in an airplane right? JB Weld? Wow! With all due respect you may want to think about raising the bar just a little bit more. The prop posted in the original post should be taken off and overhauled immediately. If that prop was on a certified plane it would have been off after the first few chips and fixed. Also in regards to wood props looking the same after a short amount of time, this is a picture of my prop in it's current shape. It has over 600 hours and has been on the plane since 2008. It really depends on how you treat your prop/airplane and where you are flying in and out of. But if you are flying in out of a gravel field then you must take in consideration that your prop is going to have to be overhauled often. Please take precaution and get that prop fixed.
photo3.jpg
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This is (the relevant portion of) the reply I got from Nicole at Cato:
Your propeller is repairable. We recommend you clean the area, warm it up slightly with a heat gun or a blow dryer and use JB Weld. Put a piece of tap on the back side of the propeller that protrudes over the edge of the prop so you are able to fill the area. Once it has cured sand back down to the contour of the blade.
Click to expand...
I am going to do this repair, and order a replacement prop with the metal tips before next flying season (I'll probably order it in the fall). This at least lets me keep flying this season (I just started).
I've asked Nicole whether I should worry about the effect of the repair on prop balance, or whether this would be fairly insignificant. I've also asked her advice on paint. I'll post back the reply.
 
Phil,

Don't pay attention to the comments about JB Weld being a hack. It is a strong and reliable compound that should adhere well and create a strong repair. It is a strong compound that is not likely any weaker than the composite material that chipped off.

I advise you to clean thoroughly with a strong cleaner and nylon brush, as grease and oil will prevent adhesion.

Heed the instructions on the container. They offer some tips for letting the liquid set up for a bit to avoid running. The cured compound is tough to sand and I would recommend experimenting with a file to get close and finish with sandpaper. Use tape to protect the finished surfaces.

Good luck,

Larry
 
I like to clean with lacquer thinner, but others will work. With L/T you need to be careful of painted surface, but I suspect on the prop they are two part and therefore will take the L/T.

Just use a strong degreaser like simple green and rinse thoroughly. Leave time for the water to evaporate.

Larry
 
Don't mean to steel the thread but for future builders reading this a metal Sensenich prop would not have this erosion cause by rain. I'm not usually outspoken on decisions where there are pluses and minuses and it may be difficult to say which is best for your flying but for me I'm glad I went the way of a metal prop. Just my 2 cents.

Good luck on your repair.

Jim
RV9a
 
The same prop at 100 hours or so.







After 1,100 hours.






I am not saying it's the way to repair but West System epoxy worked for me. Built up a layer it looks and acts like a leading edge protective tape. Been through visible moisture numerous times. Gravel and grass on regular basis.
Will wear this prop with the engine and order a new three blader from Catto again. Very happy camper here :)







 
Hi Vlad,
I'm having trouble interpreting what I'm seeing in the second picture... is that the prop taped-off prior to your working on it?
So you used straight west-systems epoxy resin to coat the edge (i.e. no microlight or any type of filler?). Did you paint the edge after coating? If so, what type of paint did you use?
Thanks for the post!
Phil
p.s. to all, I'm getting a quote for a replacement prop from Catto (with nickel edges), but I fear the new design may mean I need a new prop extension and possibly modifications to my spinner? The cost could start to really creep up :(
 
prkaye said:
Hi Vlad,
I'm having trouble interpreting what I'm seeing in the second picture... is that the prop taped-off prior to your working on it?
So you used straight west-systems epoxy resin to coat the edge (i.e. no microlight or any type of filler?). Did you paint the edge after coating? If so, what type of paint did you use?
Thanks for the post!
Phil

(
Click to expand...

Affirmative on all counts Phil. No paint it's plain west system several coats. Looks and feels very smooth all nicks buried but visible.
 
Ya'll really should bead blast a sample of hard urethane and a sample of cured epoxy. They're both simple two-part coatings.
 
Vlad said:
I am not saying it's the way to repair but West System epoxy worked for me. Built up a layer it looks and acts like a leading edge protective tape.
Click to expand...

This is a great idea Vlad! I had purchased some prop tape, but I bet this is much stronger. I think that I will coat my Catto prop before installing it on the 6A I am building.

To the original poster, I would still fill the gaps from erosion with JB weld before applying the epoxy. While JB weld is also an epoxy, it contains strong fillers that would represent a better fill for your erosion.

Larry
 
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Phil,
Keep in mind that an order for a new catto prop may state shipped in 3.5 months but this is best estimate only. My experience is that it may take a little longer so I would order once you have the funds available.

Pat Garboden
Katy, TX
RV9A N942PT
 
My advice to anyone trying to plan for a Catto propeller is to talk with Craig or his office staff. Depending on what you want and when you *need* it, it can take a longer or a shorter than many anecdotes.

In my case, I was ordering a not-common 2-blade but a common paint scheme. The time from "order" to "shipped" was 5 weeks.
 
Catto Prop

I should be picking up my new to me Catto 3 bladded with Nickel Leading edge on wednesday across the border.

I got my ''old'' 3 bladded Catto overhauled and sold it to a gentleman here on VAF.
I purchased the new one in early January specially with the metal leading edge to avoid the potential damages seen here while flying IFR in the rain.

Can't wait to try it and compare the results with the old one..

Bruno
[email protected]
 
Hey Bruno, Did you have to get a new prop extension and/or have your spinner modified at all for the new Catto design? I'm still waiting to hear an answer back from Catto on these questions.
 
Just to let you guys know, I've ordered a replacement from Catto, with the Nickel leading edges. This will take about 3 months, so I'm going to do the JB-Weld repair as an interim solution. This way I will have the spare prop as a backup, or as a decoration ;)
 
prkaye said:
I will have the spare prop as a backup, or as a decoration ;)
Click to expand...

LOL!

I had my old propeller refinished with the expectation of selling it. It's been on my wall ever since. It looked so good, I could not let it go. (Good plan since I did need to temporarily bolt it back on the airplane for two weeks.)
 
Catto Prop

Hi Phil
''Hey Bruno, Did you have to get a new prop extension and/or have your spinner modified at all for the new Catto design? ''
-------------------------------------------------
I bought a new spinner kit even tough Craig told me the old one might fit fairly well.I didn't want to take the chance of having a gap around the blades.

I think that I bought the last 12'' kit Craig had in stock after selling my old one and being told by Vans that they no longer had them in stock...It gave me a few days of worries..

I sure hope that the extension I have will still fit . Craig said that the dimension were the same but the diameter went from 64'' to his new 67''

I'm going to pick it up tomorrow and put it on on Friday..can't wait.

Bruno
 
Hey again Bruno, this is what Craig replied in response to my question about the fit of the new prop with my existing setup:
Yes, the new prop will be compatible with the Saber extension. Our new blade is a bit thinner, but we have retrofit crush plates that will bring it back to the old thickness, for guys like you. No modification to the spinner, everything will fit back in place.
... we will include the extra 5/8 crush plate and then you will be able to use all your existing hardware including the propeller bolts.
Click to expand...
I'm not too worried about a bit of an extra gap around spinner cutouts at the roots of the blades - I doubt the effect on performance would be significant.
Let me know how yours turns out!
 
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Catto Prop

Hi again Phil

Well I picked up my prop today across the border and what a nice piece of art it is...WOW..

I have a 4'' prop extension on my -4 so I hope that the prop will fit as it used to..Craig never mentioned to me that I will need any new hardware with this new prop.Gonna put it on tomorrow so I will find out soon enough..:(

Can't remember the thinknest of the crush plate, I will say 1/2'' not I'm not 100% sure.

A+

Bruno
 
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DanH said:
Ya'll really should bead blast a sample of hard urethane and a sample of cured epoxy. They're both simple two-part coatings.
Click to expand...

OK Dan I give up. You seem to be indicating that a urethane repair would hold up better than the epoxy method. I have Googled urethane and even specifically searching metal coating I find mostly wood coatings. The best I come up with is 3M Scotchkote 165BG. Is there a Urethane available that would work well for this? Point me in the right direction.
 
Catoo Prop

Hi again Phil

''Can't remember the thinknest of the crush plate, I will say 1/2'' not I'm not 100% sure.''
---------------
Well I tried to install my new prop yesterday but before I did, I called Craig at Catto Prop to make sure my old crush plate ( 3/8 inch ) will work and Nicole told me that a 5/8 '' plate is now required and should be in the spinner box....

Guest what...no plate so she told me that she will call Saber right away and get one ship directly to me asap...

So I'm back to square one for now...

So make sure that there is one included before they ship your new prop..

Bruno
 
MarkW said:
OK Dan I give up. You seem to be indicating that a urethane repair would hold up better than the epoxy method. I have Googled urethane and even specifically searching metal coating I find mostly wood coatings. The best I come up with is 3M Scotchkote 165BG. Is there a Urethane available that would work well for this? Point me in the right direction.
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I believe that Epoxy is going to be harder and more abrasion resistant than Urethane. You also need a filler for strength in a repair. This is why the JB Weld was recommend. It has steel and other fillers.

If you are just coating for abrasion resistance, either Epoxy Urethane should hold up well, but my bet is that the epoxy is stronger. For the repair, I would stick with JB Weld. I know guys that have patched crankcases with this and it holds up well and much stronger than straight epoxy or Urethane. JB Weld is strong enough to thread and hold bolts.

Larry
 
Well the repair seems to have gone quite well. Sanding the JB-Weld wasn't nearly as tough as I thought it would be. I let it cure for about 30 hours, and it sanded quite easily with 100-grit sandpaper, and then 150 to finish it. I got the contour along the edges quite smooth with the rest of hte prop. Then I masked and painted... the thickness of the paint has left a little ridge I can feel along the edge with my finger, but I very much doubt this will affect peformance. Unfortunately the black and white paint I got don't exactly match the rest of the prop, but I'm not overly worried as it's just along hte leading edges. I'm going to let the paint dry a couple of days and then put a coat of West Systems clear epoxy along the leading edges, just a an extra protectant (instead of tape).
 
MarkW said:
OK Dan I give up. You seem to be indicating that a urethane repair would hold up better than the epoxy method....Is there a Urethane available that would work well for this? Point me in the right direction.
Click to expand...

Mark,

Didn't forget about you. I've been digging around on my hard drive and checking shop shelves.

Circa 2002 I was designing a prop and prop hub (a modified SAE3) for the M14. Needed to be good for about 1500 ft-lbs minimum, 2000 being better. The wild card (where the engineer bets his *** on an assumption) is a valid figure for coefficient of static friction. It's not based on wood-to-metal friction, but rather the friction of whatever was used to coat the wood. One of the prop shops had experimented with coating the friction face of a wood prop with a thin coat of hard urethane rather than a varnish. It tested great, providing a nice bump in CoF (settled on 0.5). Same shop was casting hard urethane leading edges on maple props. Both applications were quite durable in my experience. I tell you all this because you should know I didn't just pull the idea out of my butt ;)

Which brings us to now. As I recall, the material in use then was from Cytec/Conap, but the product number seems to have disappeared with a batch of email in a drive crash. Nor can I find anything on my shop shelf. Sorry, no particular recommendation.

A quick search turned up this from Ed Sterba:

I use Urelite 3503 available from American Industrial Plastics Daytona
Beach, FL 386-272-5335 I put a plastic form on the bottom of the prop and pour the urethane along the edge. The form is a piece of plastic corner edging used for panel the walls of a house. You need to wax the form or it is on for life. The leading edge of the prop is beveled top and bottom with a coarse rasp for adhesion. It tries to escape for about 15 minutes. The next day, it is like an eraser in hardness. Hope this helps,
Ed

...and this from Sensenich (http://www.sensenich.com/products/item/167):

Propeller leading edge protection is provided by an inlaid urethane leading edge, which is cast in place on the blade with no aerodynamic penalties.

Steve Boser is a heck of a nice guy. Call and ask what Sensenich is using these days.
 
http://www.eaavideo.org/video.aspx?v=2111048001

Any good laminating epoxy should do the job. Mix in some fumed silica (cabosil) and cotton flox. Coat with neat resin then apply bog before cure. Add more cabosil if necessary to prevent running. The big secret is the mill file for contouring the leading edge to shape. Rebalancing is also a good idea.

Dino
 
http://www.eaavideo.org/video.aspx?v=2111048001

Any good laminating epoxy should do the job. Mix in some fumed silica (cabosil) and cotton flox. Coat with neat resin then apply bog before cure. Add more cabosil if necessary to prevent running. The big secret is the mill file for contouring the leading edge to shape before sanding. Rebalancing is also a good idea.

Dino
 
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