How To Fix A MT Composite Propeller

My jack lowered (user error) and the airplane came to rest on the single propeller blade. The blade was pointing strait down when the engine lowered and the propeller blade bent a bit. Naturally when I jacked the airplane up again the blade straitened right out and now there is a delamination of the tip of the blade...in other words the front surface of the blade is separated from the back surface of the blade

I hear that these propellers can be fixed by simply injecting epoxy down into the crack and glueing it together.

Has anyone done this type of repair?

My plan is to use a syringe and shove some epoxy down into the crack as far as I can inject it and then clamp the blade together until it dries and then dress the edges as necessary.

Any advice???

SL 32 R1

Go to www.mtpropeller.com Find the above referenced document under Service Letters. The letter details damage that is field repairable, but my guess is that you need to talk with one of the three MT Service Centers in California.

Best regards,

Merrill

Stating the obvious, but propeller tips spin super fast and take significant stress loads. In the interest of helping to make sure your prop is safe, my advice (for what it's worth) would be to ask MT directly, rather than guessing or asking for repair methods here, to be honest. Certain airplane parts are critical and the authoritative source is the place to go. MT has dealt with resolving multiple real-world issues and knows exactly how the blades are designed and how they can fail in various conditions.

That said, I'm sure people would like to know what you find out when you get an answer from MT.

Thanks for the response and advice. Naturally I was hoping that someone would respond and say "oh...I had the same thing to me...I just glued it together with expoxy and it has worked flawlessly for years"

Call Brian at Sullivan Propellers in Hayward - (510) 782-0920.

They have experience of MT props and will give you honest advice.

Composite Propeller

I hit my propeller on the ground during an engine out. I loved the Cato propeller and asked Craig and he did not want to try to repair it. So I learned how to vacuum bag composites under heat.
I used a refrigerator box and a milk house heater with a thermostatic switch to control the heat.
I bought a vacuum pump from harbor freight.
Bought aluminum tube fittings from aircraft spruce.
Purchased epoxy from Max Clear composites.
Max Clear composites specialist instructed me how to put the bag over the propeller and then to the pump.
I heated the inside of cardboard refrigerator box to 165 degrees and put the propeller inside while the vacuum pump was running the whole time.
The propeller came out just like new, very hard. I had to sand the rough spots and use a small amount of body filler to make it smooth and then painted it. Then balanced it.
It works great and I fly it often and have about 150 hours on it so far.
I'm now thinking of making my own propellers from now on.
Balancing the prop video https://youtu.be/i6im5MDnb8g
Homemade Vacuum bag oven https://youtu.be/6Qm9o_QrtCA

my two cents

Vans101 said:

...

I hear that these propellers can be fixed by simply injecting epoxy down into the crack and glueing it together.

Has anyone done this type of repair?

...Any advice???

Click to expand...

Can you make a repair? Yes. That said, my best advice is to compare risk to reward:

Reward:
1. You would avoid the cost of a repair by a professional.
2. You would have an opportunity to learn.

Risk:
Will it hold up? I don't know, and you may not either.
That means every person in the airplane, around you, and under your flight path, is exposed to an unknown risk of prop failure on the ground or in flight, every time you start the engine.

Small chip on tip?

What about a small - 1/4" chip out of the end of one of the tips? Mine was under the bed waiting to be installed and the vacuum glanced off the tip and made a little chip. Similar to what you would do making an arrowhead. It is a Catto 3 blade, but imagine they are all made the same.

I will send a picture to Craig and get his response. There was a Malibu that lost its prop over the mountains near Aspen several years ago and the pilot and 3 passengers were VERY lucky he was able to make it to the airport and safely land.

http://www.aspentimes.com/article/20071227/NEWS/27569632

RV3bpilot said:

I hit my propeller on the ground during an engine out. I loved the Cato propeller and asked Craig and he did not want to try to repair it. So I learned how to vacuum bag composites under heat.
I used a refrigerator box and a milk house heater with a thermostatic switch to control the heat.

Click to expand...

I'll give you a ton of credit for your ingenuity accomplishing a repair and balancing.

However, as Esco eluded to, when the manufacturer of the prop says its not repairable, you should probably listen to his advice.
Propeller blades are exposed to huge forces and generally cannot be repaired if damaged beyond certain limits, generally limited to minor nicks, chips or dings.

Hate me if you want but the reality is you are likely to become an accident statistic if you continue to fly with this prop.

The prop should be sent to MT for a tear down and inspection.

prop loss

Let me give some advise on losing a prop its not worth the risk if a tip comes off the prop will likely come off shortly after. My prop departed my RV6 from another part failure after that you get to BUY a new prop tear your engine down to recertify all parts rebuild engine repair cowl and repaint.Thats if you make it to the ground and are still in one piece kind of hard to see where your going with oil covering windshield.After flying for 35 years it was a real eye opener its really more than something that just goes round and round up front its there to keep the pilot cool.
Bob

Not sure who said this, think it was a WASP from WWII, "The propeller is a cooling fan to keep the pilot cool. When it stops or leaves the airplane, the pilot begins to sweat".

I have some minor hail damage to my Catto prop. Contacted Catto to find out the best way to repair it. Will go with their advice. Hopefully not needing a new prop.

However, as Esco eluded to, when the manufacturer of the prop says its not repairable, you should probably listen to his advice.
Propeller blades are exposed to huge forces and generally cannot be repaired if damaged beyond certain limits, generally limited to minor nicks, chips or dings.

Hate me if you want but the reality is you are likely to become an accident statistic if you continue to fly with this prop.[/QUOTE]

We all just lost Ron Alexander and his friend in a fatal accident due to a wooden prop blade separation. It had been recently repaired as well.

Prop blade repair is nothing to fool around with. 150 hours is nothing, actually. Recently there was a complete engine failure on an engine that had been top overhauled 150 hours prior. A cylinder came loose due to insufficient torque of the base nuts.

I agree with Walt on this one.

Vic

mbauer said:

Not sure who said this, think it was a WASP from WWII, "The propeller is a cooling fan to keep the pilot cool. When it stops or leaves the airplane, the pilot begins to sweat".

I have some minor hail damage to my Catto prop. Contacted Catto to find out the best way to repair it. Will go with their advice. Hopefully not needing a new prop.

Click to expand...

Mike, I had a small chip in the end of one of my blades. I would never blame anyone (my wife) for hitting it with the vacuum cleaner wile it lived under the bed because I may be spending more time with that same vacuum for complaining. Whatever, it got chipped. I sent this photo to Craig and he said - use some JB Weld or epoxy on it, sand it, and paint it. I fixed it and now I can't find which blade it was.

Let me know when you are going to be back in the area!
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Small dings like this on the tip are OK to repair.
Cracks or gouges further down the blade can have a lot of stress that can lead to blade separation.

Vic

Some More Advice

Part of my father's job as a metallurgist for one of the auto companies was to testify as an expert witness in product liability cases. I can recall a case many years ago when a fan blade failed while a mechanic was working under the hood. A piece of a blade hit him in the head and caused catastrophic injury. The subsequent trial and metallurgical examination determined that the owner had previously bent the fan and decided to straighten it rather than replace it. For the sake of a few dollars, a number of lives were changed forever.
Ask the manufacturer - he has real flesh in the game. If he says it's OK to repair (hard to imagine without a very detailed examination), make sure you've got it in writing. If you decide to repair it on your own, you've accepted responsibility for any injuries a failure may cause. Of course, my opinion is just that.
Terry, CFI
RV9A N323TP