Serious question: Do you still chase borescope readings or go with feel now?

I used to spend like 20 minutes per cylinder getting a perfect borescope image on every annual. Then last year I had a Continental IO-520 that looked perfect on the scope but had a cracked ring we found by feel during a compression check. Now I do a quick visual and spend more time running my fingers around the ring gaps and looking for carbon tracking on the spark plugs. My mentor swore by the borescope and I felt like I was cheating at first. Has anyone else stopped relying on cameras so much and gone back to hands-on methods? What made you switch?

2 comments

2 Comments

lee_butler17h ago

Used to think the borescope was the ultimate truth, but your ring gap example hit home. I had a similar thing with a Lycoming O-360 where the scope showed a clean cylinder but I felt a scratch with my fingernail that turned into a scored wall after removal. Now I start with a quick flashlight look, then spend real time with my fingers on the ring gaps and plug threads. The scope is still good for valve guides and exhaust ports, but I treat it more like a second opinion than the final say.

king.jordan18h ago

You ever run your finger along a cylinder wall and feel something that doesn't show up on camera? That's what got me. Found a hairline fracture that way last summer. The borescope just showed normal carbon deposits. My hands found the catch. Now I use the scope for checking valve seats and guide wear but I trust my fingers more for ring and cylinder condition.