What’s a Simple Way To Detect Oil Leaks in an Aircraft?

On small aircraft with piston engines, engine oil leaks are a fairly common problem. We’re talking about small airplanes such as those from Cirrus, Cessna, Beechcraft, Diamond, Mooney, or Piper.

An engine from a small airplane with a bit of an oil leak going on | A featured image from "What’s a Simple Way To Detect Oil Leaks in an Aircraft?" |
Low levels of oil due to leaks should be identified right away, as these can cause major engine damage if neglected or left unattended.

To quickly detect oil leaks in your small aircraft, you may either use a UV flashlight or a UV dye kit– both of which are readily available online. Ultraviolet blacklight can reveal leaks as a bright fluorescent yellow or green glow.

Routine inspection, quality control, or troubleshooting procedures of all external surfaces, pipework, joints, and coils using UV light offers an improved probability of fluid leak detection.

Why Is It Important to Check for Oil Leaks in My Aircraft?

The oil used in an aircraft engine performs various critical functions such as:

  • Protect it from corrosion and too much heat.
  • Lubricate the components and propellers.
  • Reduce noise.
  • Maintain the engine and other components clean.

However, the oil’s most important purpose is lubrication–and without it, all the moving parts would quickly wear out.

If the engine is the “heart” of your plane, think of oil as the “blood” of your aircraft that keeps everything functioning. And if you see a trickle of it anywhere near the wheel pants or cowling, it means that your plane is bleeding. And just as you’d never ignore a bleeding gash, you shouldn’t disregard an oil leak as well.

Hack #1: Using a UV Flashlight

But sometimes, the oil leak is not easily visible, especially in certain lighting conditions. Fortunately, the engine oil contains UV dye that glows under a UV flashlight, making it easy to detect the source of the leak without removing the engine, dropping the transmission, or doing any time-consuming task everyone loves to hate.

This simple hack is also a lot easier than cleaning the entire engine just to detect where the oil leak is coming from.

Sometimes, you need to start the engine and run it for a bit. Once you shut it down, identify where the leak is coming from using your UV flashlight. (Some people do this with the engine running, which is not really advisable unless you’re extremely careful or a pro.)

To have a better view of the oil leak’s source, you may want to use oil additives to make the oil glow brighter; however, even without this additive, you can still notice that the oil shines bright enough under a UV flashlight.

Hack #2: Using UV Dye Kits

Another option is to buy UV dye kits that usually come with a pen UV light and yellow-tinted protective glasses (they cost around $15-$20 on Amazon). These cheap tools are really helpful in detecting the source of oil leaks in your aircraft.

Are Some Oil Leaks More Dangerous Than Others?

Take note that not all oil leaks are created equal, so to speak.

If the leaked oil has a dark brown or black color, it usually means that it came from the engine and may pose serious safety issues that warrant additional investigation. But if the leak has a golden brown color, most likely it is just a “mess” or spillage made by someone who just added a fresh oil to the engine.

Oil leaks don’t get better by themselves, and so they always warrant further inspection. If you see one, make sure that you inform your mechanic or flight instructor just to be sure that it doesn’t lead to safety issues.

Detecting oil leaks with a UV flashlight | A featured image from "What’s a Simple Way To Detect Oil Leaks in an Aircraft?" |

A Final Word About Detecting Oil Leaks Early

They say an ounce of prevention is worth a pound of cure. And that old adage rings particularly true when it comes to oil leaks and regular airplane maintenance.

Since oil leaks can be so destructive, the cost of repairing the leak is almost always worth it to make sure your aircraft stays in top shape. If a check of the engine reveals that the oil level is low, the leak problem should be diagnosed promptly to prevent potential damage to the engine.

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(Source: Cessna Owner Organization)