By Scott Sellers

This article is a follow-up to “Introduction to Borescoping: Part 1,” which explains how owners can use borescope images to change the way they monitor cylinder health, allowing them to take preventative steps before serious issues occur. The preferred inspection interval is 100 hours for nor­mally aspirated engines and 50 hours for turbocharged engines.

The following information comes from an interview featuring borescoping pioneer Dave Pasquale in Episode 5 of the “Beyond the Hundred Dollar Hamburger” podcast on, hosted by my brother, Mark Sellers, and me. Dave is a veteran A&P/IA and the originator of cylinder inspection reports, so he’s an expert on this subject.

General Notes

  • With this cylinder borescoping process, you will be taking eight photos for each cylinder, numbered #1 through #8.
  • Organizing your images matters, since you’ll be accumulating quite a few. You may find it helpful to create an image folder for each cylinder, which makes it easier to compare images from year to year.
With the top cowl and top spark plugs removed, set up your borescope and laptop so there’s easy access to the engine. I like placing the borescope on a rolling cart. Launch the Ablescope or Windows camera app, whichever you prefer, on your laptop. Look through the spark plug hole with the tip of the scope positioned just far enough in so you don’t see the spark plug threads. Use the scope as the light source and manually turn the engine to position the piston at the bottom of its stroke.
Take Photo #1 of the piston face, looking for impact damage, melted edges, or an oil film.
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