Frequently Asked Questions. We’ve assembled some of the most common questions for all the builders and pilots out there.
Speed | Altitude | STOL | Performance
How Often do you check the torque on a Catto Propeller?
After the first 10 hours after the very first install and every six months with season change and at annual.
What are the small imperfections on the hub?
This is where we inserted lead for balance. We start balancing the propellers in finish but we also do a static balance once the propeller is complete. These are holes that we drilled to insert lead.
Can you re-pitch a propeller?
Yes, we can increase and decrease the pitch up to three inches.
Decreasing the pitch: When we decrease the pitch we sand a little bit of material off the back side of the blade along the trailing edge. The amount of material that we remove is minimal and it doesn’t change the structure of the blade. This will increase your static RPM around 30 RPM per inch of pitch. Your max RPM will also increase around 50 RPM per inch of pitch at wide open throttle. Your top speed will remain the same but it will be at a slightly higher RPM. You will also lose around 2 mph at the same RPM in cruise but the extra static RPM will shorten take off distance.
Increasing the pitch: When we increase the pitch we add material on the back side of the blade along the trailing edge. Static RPM will decrease your initial acceleration will take a little longer. Static RPM will drop 30 RPM per inch of pitch. In cruise you will gain 2 MPH at the same RPM per inch of pitch added and your max RPM will decrease 50 RPM.
What are the small cracks in my paint?
Our fixed pitch propellers are not molded which allows us to manufacture a very wide variety of propellers. Since the props aren’t molded we do a wet lay and use a filler material on top of the composite. This filler material does become brittle over a few years. The composite does flex and has an infinite fatigue life but since the filler material becomes brittle you will see small cracks in two bending nodes on the propeller. This is normal and non-structural. If you ever have concerns or questions please email pictures to firstname.lastname@example.org
What is the TBO on fixed pitch propellers?
We don’t have a TBO yet. We do recommend that you do a good visual inspection of the propeller at annual and check the torque. A lot of people will send their prop in after 6-10 years to have it refinished and repainted. Anytime the propeller is sent in we evaluate the composite, aerodynamic balance, static balance and tracking.
What are the requirements for annual?
We recommend that you set the torque wrench at the specified torque value and make sure the bolts held their torque. If torque is below spec we recommend taking the propeller off and checking the aluminum plate on the back and the other mounting surface. You are looking to see if there is any charring which is evidence of friction. If you have this please send photos to info@cattoprops and give us a call to discuss at 209-754-3553.
A good visual inspection of the propeller and nickel. Damage to the nickel or composite requires tap tests. Tap damaged areas with the back of a screwdriver or a coin to see if there is a hollow or higher pitched sound, it will be very obvious.
If you have an ELSA aircraft please see your manual for requirements.
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