Propeller Maintenance 101

The propeller is one of the most important parts of the aircraft, but it often doesn’t get the attention that it deserves. If an aircraft experiences propeller failure mid-flight, the pilot would lose control of the aircraft and disaster would ensue. If your plane has a propeller, it’s imperative that you learn how to care for it in order to prevent safety issues. Here’s everything that you need to know about propeller maintenance:

Pre-Flight Inspections

Before taking off, pilots should examine the propeller as part of their pre-flight inspection. Run your hands along the propellers to feel for dents or deep scratches in the surface. Small dings and scratches aren’t serious, but once they get to be a certain size, they can become a safety hazard. If you notice a dent that is large enough to affect the metal around it or a crack in the surface, these issues need to be fixed before you take flight.

Remove Damage

Use a hand file to remove dings and dents from the surface of the propellers. None of the damage should be visible once you are done filing. Once you are done, use an emery cloth to remove marks left by the hand file. Run your hands over the surface one more time to double check that the surface is smooth. If you have dye penetrant on hand, this can be used to find any cracks that may remain on the surface. Then, apply Alodine to the area that you have filed down, and paint the surface to protect it from corrosion.

Inspect Often

Pilots should conduct preflight inspections before every flight, but they should also conduct more thorough inspections at fixed intervals. It is recommended that you conduct thorough inspections of the entire aircraft—including the propellers—every year or after 100 flight hours, whichever comes first. By performing these regular inspections, you can catch corrosion and other damage before it seriously impacts the aircraft. 
But in some cases, you may need to conduct investigations more frequently. For example, if the propeller hits something, it should be immediately inspected for damage. Even if the object was small or the propeller was not rotating quickly, the impact could cause the blade to bend, twist, or become loose. You should also immediately conduct an inspection of the propeller blades if you believe they have been hit by lightning. Lightning strikes typically darken a small area on the surface of the blades and cause pitting, but damage may not be visible to the untrained eye. Even if you are not sure whether lightning hit the blades, it’s best to have them inspected just to be safe.

Don’t Push or Pull

Many people grab the propellers in order to push or pull the aircraft, but this is not a good idea. Use the tow bars to move the aircraft by hand. If you grab the propellers, the positioning of the blades may be affected, which will impact flight performance.

Propeller Tracking Checks

Aircraft owners should also get in the habit of performing propeller tracking checks. In order to do this, remove one spark plug from each of the cylinders so you can easily rotate the propeller blades. Adjust one of the propeller blades so it is pointing down towards the ground. Place a wooden block right at the tip of the blade. This wooden block will act as a marker to remind you where the tip of this first blade was located. Then, begin to rotate the propeller slowly so you can check the positioning of the other blades. The tip of each blade should pass within one-sixteenth of an inch of the wooden block. If a blade is more than one-sixteenth of an inch away from the block, it needs to be adjusted before you take flight. But, you should never attempt to adjust the propeller blades without the help of a professional.

Avoid Rocks and Debris

Before starting the plane, take a look around and make sure there are no rocks or other debris within four to six feet of the propeller. Rocks and other debris will be lifted into the air when the propeller blades start to rotate at idle or slow taxi speeds. When this happens, the debris can damage the surface of the propellers and delay your flight.

Skip High Pressure Washes

Propellers should be cleaned on a regular basis. But, don’t use a high pressure washer to clean the propeller blades. High pressure washers have the power to drive water into unreachable nooks and crannies of the propellers. If you can’t reach these areas, you won’t be able to thoroughly dry them after you are finished cleaning. Therefore, the water will remain in these areas and create a highly corrosive environment that could lead to serious damage.

Do Not Use Polish

According to the Federal Aviation Administration (FAA), polishing the blades of a propeller is almost always not acceptable. Polishing may remove some of the protective substances applied to the surface of the blades to prevent corrosion. As a result, surface corrosion may develop on polished blades. The FAA recommends referencing the instructions provided by the manufacturer to determine whether you should polish the blades. Unless the manufacturer recommends that you do so, you should not apply polish to the propeller.
You may not need polish to care for the propellers on your plane, but you will need it to maintain other surfaces. The next time that you need to polish your aircraft, trust the aviation approved Bright Work Polishes. The three polishes—red, white, and blue—are designed to remove oxidation, cloudiness, water spots, and scratches. By using these polishes, you can preserve the beauty of your aircraft and protect it from damage.