As an airplane owner, you are authorized to remove and reinstall your engine’s cowling, as long as it does not involve “removal of the propeller or disconnection of flight controls.”

So, have you ever wondered what to look for in there?

Listen to today’s podcast episode to learn about some key colors that can be indicators of some issues that may need corrective action.


BLUE:  Possible fuel leak… fix ASAP!

RED:  Possible hydraulic leak.

HONEY color:  Clean engine oil.

DARK BROWN oily color:  dirty engine oil.

DARK BROWN, dry dust:  steel part chafing.



Notice the dark brown dust, indicating a loose, and chafing, steel part.







DARK GRAY:  Possible indication of aluminum chafing mixed with rain water.

LIGHT BROWN:  Possible exhaust leak, especially at cylinder flanges.

TRAFFIC LIGHT COLORS:  Red, yellow, and green:  Colors to look for on exhaust valves with a borescope.

For more information on this, read the following article with AOPA, by Adrian Eichhorn:

This article is an excellent, simple explanation of borescoping and exhaust valve inspections.

Remember, when it comes to exhaust valves, GREEN MEANS STOP!

Here is a PDF document from AOPA about exhaust valves and what to look for:


And one more color:

:  The color of my personal torque putty.

Listen to the podcast to hear the story of why I use a lot of this stuff now!


Finally, if you would help me by leaving a review on iTunes, I’d greatly appreciate it!  This can help more airplane owners find the show.  Here’s how to do it:

  1.  Go to iTunes store.
  2. Search for “Airplane Owner Maintenance” or “Dean Showalter.”
  3. Click on the podcast picture or the name “Airplane Owner Maintenance.”
  4. Click “Ratings and Reviews.”
  5. Click “Write a Review.”
  6. Give a title, write a short review, and give a star rating.
  7. AND, if you include your real name in the body of the text, and anything else you’d like other airplane owners to know I will try to recognize you in a future episode.
  8. Thanks!


So…  go take a look at your airplane engine, and see if you have any “Tell-Tale colors” that need to be addressed!

Have  a great week!