What It Looks Like

When A Propeller Has Been Dressed

You might not associate propellers with getting dressed, but dressing is a normal part of good propeller maintenance. If you notice that a propeller blade has one or more smooth gouges in the leading edge, it's a sure sign that a mechanic has dressed the prop by filing out nicks or chips.

Propellers operate in a harsh environment, and some minor damage is inevitable. Typically, the leading edges will show some wear from encountering sand, small stones, or other hard debris. This is especially true if the airplane is flown into or out of unimproved strips or if there is loose stone or gravel on the ramp or runway.

Any visible damage to a propeller should be repaired. Dings, nicks, and scratches can be starting points for tiny cracks and/or corrosion that could grow and, in the worst case, lead to blade failure. Minor damage to an aluminum blade is repaired by removing material. Composite-construction blades are repaired by filling in the damaged area with new material. We will limit this discussion to aluminum blades, which you are more likely to encounter during your training.

A local mechanic can repair minor damage without removing the blade from the aircraft. Guidelines determine what can be repaired and how to repair it. For example, a quarter-inch-deep nick in the leading edge should be filed out to a distance of one and one-quarter inches on either side of the nick, resulting in a smooth, blended depression. The filing should be deep enough to remove any metal. Also, the finished repair should maintain the general shape of the original propeller airfoil.

Scratches in the camber (back) and face of the blade are repaired in similar fashion, but with different depth requirements. In this case, the finished depression created by the repair should be 20 times its depth, whereas a leading edge repair should be 10 times longer than the depth of the nick. Any repairs should be finely polished and repainted if applicable.

When preflighting the airplane, run your hand along the leading edge, face, and camber of each blade. If you feel sharp edges, nicks, or dings, consult a mechanic before flying.