Catto 3 blade coming apart

[CattoPropellers]

I want to make some corrections in the postings about the Catto Popellers with the nickel leading edges. The propeller in question was a 2 bladed propeller on a Glasair, and the propeller did not come apart. We have an excellent reputation for structural integrity of our propellers.
The owner had contacted me about a small crack found in the nickel during a preflight inspection. My return email recommended that the propeller be returned for repair or replacement. Due to a shortage of nickel at the time, the owner was told it would be at least 4 weeks before we could do the repairs or replace it. The owner elected to continue to fly the aircraft. The nickel that separated from the propeller was a 7? tip section that weighed 32 grams.
This 320 engine was of high compression and also had electronic ignition. If you modify your engine from ?stock? to high compression and electronic ignition, you are also modifying the natural frequencies of the engine. This can be catastrophic with a metal propeller. Even the standard metal propeller on the standard 320 has RPM restrictions because of this. After about a year of testing and tens of thousands of dollars invested, we now have one of the most advanced Data Acquisition Systems available to do vibration surveys on propellers. It was this DAQ system that we developed that was recently used in the ASTM LSA vibration survey of the CarbonCub propeller. Catto Propellers is the first to comply with the latest requirements set forth by ASTM. (the regulatory system for LSA aircraft)
Once we had the cooperation of the engine manufactures with vibration data and the ability to perform these advanced vibration surveys, it was found that the natural frequencies of the earlier design of the propellers coincided with the natural frequencies of the engine. Most can relate to a metal propeller on a 360 engine with the yellow arc at 1950-2250rpm. This is the same reason why an all metal prop on the RV 320?s has the 2600rpm limitation. Once we modified the laminate schedule of the propeller blade which changed its natural frequency, this solved the issues with cracking.
It is impossible for us to do a vibration survey on every installation of engine type, engine modifications, change in compression ratios and change in timing by electronic ignitions. However, what we do know now is operating at high compression ratios and having electronic ignitions with the early design of propellers could be subject to having the nickel crack. As always, diligence should be used during preflight inspections.
One post speculated that I did not recommend nickel because of possible problems. This is not true. I recommend in certain circumstances that the customer install the propeller without the nickel at first in case they desired a pitch modification. In order to install the nickel, we must also repaint the propeller, so it much easier and less costly to do it all at once.
In the world of experimental aircraft, we do all that we can to insure the propellers are operated in a safe manner and tested to insure safe operation. Unlike certified aircraft, you have the pleasure of changing design to your liking, includes engines and electronic ignitions. Sometimes when these simple changes are made, there can be consequences that must be considered. The important part of all of this is the learning, and making changes accordingly to insure the safest operation.

[DougJ]

Great post Craig, thanks for jumping on board. Im the new owner of an O-320 powered RV-6 down in Fresno and I figured I would be talking to you about a prop. I'm actually pretty satisfied for now with the Warnke that came on the airplane, so a prop has moved down on my list of priorities.

I still want to come up to Jackson and see your operation at some point though.

Doug

[pmccoy]

Craig-

Thanks for the update. I am running an IO-320 with electronic ignition that has variable timing. I will continue to closely inspect the prop with your nickel plating during my normal preflight inspection. So far I only have 42 hours, and the prop is working great.

[celstar]

50 some hours on my three blade Nickel with a O320 and Lightspeed Plasma 3 and could not be happier. The only time I will maybe change prop is when and if Craig makes a constant speed prop.

[LarryT]

Has Catto Propeller completed their relocation? To what airport are they relocating?

Larry Tompkins
544WB -6A
W52 Battle Ground, WA

[David-aviator]

Don't know which airport this guy came from but he did arrive yesterday via Fedex and will reside in an upstairs bedroom until his assignment is activated.

I had an informal briefing by Nicole a couple weeks ago regarding the substance of this thread and have no qualms whatever about the prop - with or without the nickel, had the same prop without nickel on the 7 and was very satisfied with it.

This unit has the nickel as you can see, but what you can not see is a plastic boot shield from the hub to where the nickel starts, it should be very impervious to rain. The nickel extends farther out to the tips than one could get a plastic boot with the non-nickel blades.

I would order another one in a heart beat, these props are a good value for a simple, light weight operation.






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[db1yg]

That upstairs guest is BEAUUUTIFUL!

I also have a great deal of confidence in Craig's designs. Been a happy Catto 3 blade driver for 7+ years!

Cheers,

db

[Bob Kuykendall]

Originally Posted by LarryT

Has Catto Propeller completed their relocation? To what airport are they relocating?

Larry Tompkins
544WB -6A
W52 Battle Ground, WA

Craig can chime in and correct me if I'm wrong, but I've heard that he's relocating to Calaveras County Airport (CPU) in the scenic western foothills of the Sierra Nevada.

Edited to add: I was wrong! See post below; Craig is moving to Jackson, the next big town north.

Thanks, Bob K.

[CattoPropellers]

Hello! We will be moving to Jackson Westover KJAQ in late August!

[Zero4Zulu]

Are Catto Props suitable on a O-320 with 10:1 compression with Mags?