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How to Find the Right Propeller for your Project Plane

Date: December 26, 2019 Category: Blog Tags: , , , , , , , ,
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Dreaming of building your own airplane? You’re not alone. According to the EAA, more than 33,000 amateur/homebuilt aircraft are currently registered with the FAA, and many projects are likely still in progress in garages and basements around the world.

Beginning a homebuilt project is a big commitment, but it’s well worth the effort. While the average homebuilt aircraft takes between 1,000 to 3,000 hours to build, anyone who’s successfully completed a project will tell you that it’s among their proudest accomplishments.

Homebuilders have a choice of starting from scratch or using a kit. A kit seems like the natural route if you want an easier means of building the plane. But even with a kit, there are many choices to make, including selecting the aircraft propeller to install.

Choosing a propeller is a critical decision that will affect the performance, efficiency, and appearance of your project plane. It pays to do some upfront research to be sure the propeller your choose matches your needs and mission.

Here are some of the most common factors homebuilders should consider when picking an aircraft propeller for their project plane:

Powerplant combination

When it comes to powering your airplane, the engine and propeller must work well together. If you’re building a less-common design with a certified aircraft engine (i.e., Lycoming or Continental), the best approach is to copy the “firewall forward” off of a certified, factory-built aircraft. If you’re using a kit, see what the kit manufacturer recommends or check out what other builders are doing with the same aircraft and engine. This will take much of the guesswork out of your powerplant installation.

Propeller material

Propellers are typically made of three types of material: wood, aluminum, or composite. Fixed pitch wooden propellers are generally the least expensive option, but these come with a number of drawbacks. Wood will swell and shrink with humidity fluctuation, which can lead to loosening of bolts, and ultimately the prop itself. Wood can also erode with rain, and the blades will need to be refinished every couple of years. Performance-wise, a fixed-pitch wooden propeller will not be able to provide optimal performance in all flight conditions.

Aluminum blades are heavier, but they will handle rain and debris better than wooden props. They are durable and, while more expensive than wood, still a reasonable price.

Composite propellers are the latest in propeller technology. They offer excellent performance and lighter weight, and while they will cost more than the other two types, they are made to be highly durable and long-lasting. As today’s kits advance in sophistication and performance, composite propellers are in high demand.

Certified vs. non-certified props

Using a non-certified aircraft propeller usually requires an expansion of the FAA Phase I flight testing period from 25 hours to 40 hours, even if the engine is certified. The additional hours will slow your project’s progress, but that isn’t the only reason for going with a certified prop.

Certified aircraft propellers go through an extensive testing process to ensure proper strength and endurance against fatigue problems. They offer less risk than non-certified props when used with an approved engine combination. If you want peace of mind, choose a certified prop from a reputable propeller company.

New or used propellers

Purchasing used parts and materials can be a smart way to save some cash on your project plane. However, be extremely cautious when buying a used aircraft propeller. Even if the prop appears to be in good condition, it could have internal damage that is beyond repair limits. Look for a used prop that has been recently overhauled by an FAA-certified repair station; it will have a yellow tag with it that identifies the propeller and states when it was overhauled.

If you find a used propeller you want to purchase, consider the following:

  • If the propeller doesn’t have a logbook or yellow tag, pay to have it overhauled. It’s the only way to be sure you’re getting a quality used prop.
  • Props with bent blades are suspicious and should be checked out by an authorized propeller repair station before purchasing.
  • Don’t try to straighten bent blades yourself. Some aircraft propellers are too bent to be adequately fixed.
  • Too much corrosion, particularly around the hub, is usually not sufficiently serviceable.
  • Any signs of welding on an aluminum blade is a non-starter. Walk away.
  • Composite propellers with damage need to be assessed by a technician with experience in that type of propeller. A trained expert will be able to tell you if the propeller can be repaired.

While you can save money with a used aircraft propeller, prepare to have it checked out by a reputable shop with expertise in the propeller type before making a purchase.           

At Hartzell Propeller, we work with the world’s top kit manufacturers to design aircraft propellers suited for their recommend engine for the kit. Our aircraft propellers have been designed and tested to meet rigorous standards and provide homebuilders with better safety, efficiency, and performance. Often, you can purchase a new Hartzell prop for your kit plane directly from the kit manufacturer, sometimes at a special price when bundled with a new engine. Not only is this choice less risky, but it can also help you save money.

If you have questions about the proper propeller selection for your homebuilt aircraft, please contact us today.

Hartzell Propeller