Carbon Fiber Propeller Tip Repair

by | Apr 24, 2019 | Mx: Motor, Mx: Troubleshooting

Ding the tip of your carbon prop? Is the prop in good shape otherwise? This may work to repair it if the damage is minor. It’s based on the same technique as covered in Chapter 12 of the PPG Bible.

Flying a repaired prop could cause injure or kill a bystander if it comes apart! Take this seriously and don’t do it if you have any reservations or it doesn’t fall within the limits listed here. Even if it does fall within these limits it may come apart for any number of reasons.

If in doubt, change it out!

Adhere to the following limitations and cautions unless you’re willing to hurt yourself or others.

  • Don’t try to repair damage to more than 2 inches of the tip(s).
  • Don’t use this technique for damage other than the last 2 inches of tip.
  • If there is any indication of stress fracture or structural compromise, toss it. Carbon fiber props may very well have crushed parts of the interior honeycomb structure.
  • Do test runs in safe areas. Departing pieces will go outward initially but may also go forward or backward once they leave home. Ensure there’s nothing anywhere near the prop’s plane that you want to keep intact, especially soft, fleshy things.
  • After each flight look for signs of stress cracks on your repair along with a normal prop inspection. Unfortunately, repairs are still more likely to fail without warning.
  • If a prop repair lets go in flight, it will be vibrating severely and may result in engine separation. Unless you’re over really bad terrain or large monsters are chomping at your feet, shut the motor off right away and land.

Fixing the Prop

Here are the tools, although a jigsaw is nice, too, if you’re using soft wood (like poplar) and have a way to clamp or brace the wood. We’re in a motorhome, a SMALL motorhome, so our options are limited.Belt sanders rock but be wery, wery careful, they take off a lot of material quickly, especially with the 80 grit sandpaper I use for shaping. Use a sanding block for finer sculpting of the shape then use 200 grit or so for smoothing.

Belt sander and saw for doing prop repair

Here is a summary illustration of the repair process.

Carbon fiber propeller repair steps

Below are some pictures from the actual repair. You’re looking at he prop from it’s trailing edge.