Cylinder pitting

[dreed]

Hi All-

Starting my condition inspection early this year, and since my buddy bought a new borescope we decided to take a look at my jugs

IO-390 with 250 hours (about 100 a year), but it was long term pickled for a little over 12 years before first start. We'll get better pics and I'll share, but Cylinders 3 and 4 show a little pitting. Compressions were great at my last condition inspection (78+ on all) and oil analysis looks good too over the last three reports with numbers all within or below Blackstone's averages. I use a qt every ~15 hours

Any thoughts/advice? I could pull and see if they'd clean up with a bore/hone or run and monitor given compressions, oil analysis and usage.

Cyl 3 pitting

 

[Freemasm]

Hi All-

Starting my condition inspection early this year, and since my buddy bought a new borescope we decided to take a look at my jugs

IO-390 with 250 hours (about 100 a year), but it was long term pickled for a little over 12 years before first start. We'll get better pics and I'll share, but Cylinders 3 and 4 show a little pitting. Compressions were great at my last condition inspection (78+ on all) and oil analysis looks good too over the last three reports with numbers all within or below Blackstone's averages. I use a qt every ~15 hours

Any thoughts/advice? I could pull and see if they'd clean up with a bore/hone or run and monitor given compressions, oil analysis and usage.

Cyl 3 pitting

View attachment 56522

Not feeling lucky for you on this one. Hard to tell from the pix. Are those plated barrles? Is that pitting or chrome or Ni delam?

 

[pa38112]

I would fly-on, and keep doing what you are doing: Monitor oil analysis, cylinder leak-down, Borescope condition, ect. If you are flying 100 hr/year than I believe this came from the storage period.
Savvey has a new program for reviewing Borescope photos. Watch this video:

It is worth spending the $189 to subscribe and have them take a look, but I would be surprised if they tell you anything different.

 

[dreed]

Not feeling lucky for you on this one. Hard to tell from the pix. Are those plated barrles? Is that pitting or chrome or Ni

Thanks- it's definitely not ideal but better to catch it now. They are steel cylinders, so perhaps an over bore and new piston/rings may be an option.

I'll get some better pics to share.

 

[dreed]

I would fly-on, and keep doing what you are doing: Monitor oil analysis, cylinder leak-down, Borescope condition, ect. If you are flying 100 hr/year than I believe this came from the storage period.
Savvey has a new program for reviewing Borescope photos. Watch this video:

It is worth spending the $189 to subscribe and have them take a look, but I would be surprised if they tell you anything different.

Thanks! I am actually already a Savvy subscriber, even the right level to get their opinion on these. I'll do the 11 shots per cylinder and upload them for review. Great advice!

 

[OKAV8r]

I'm guessing the Blackstone reports show elevated iron? Or, this rust is recent enough that it wasn't present at the last oil change?

 

[Dan 57]

fly-on, and keep doing what you are doing

Same advice.
My cylinders basically look the same, as the aircraft sat unflown for 2 years when I acquired her. Yet my O-360 has >70 compressions all round, good oil analysis, always starts on a quarter blade, and the oil consumption is a meager 2qts/50hrs, all for the last 1'600 hours as of today.

 

[dreed]

I'm guessing the Blackstone reports show elevated iron? Or, this rust is recent enough that it wasn't present at the last oil change?

Iron has never been elevated in any of the Blackstone reports- can't say how recent the pitting is, but my gut is that it was there due to long term storage.

 

[dreed]

Same advice.
My cylinders basically look the same, as the aircraft sat unflown for 2 years when I acquired her. Yet my O-360 has >70 compressions all round, good oil analysis, always starts on a quarter blade, and the oil consumption is a meager 2qts/50hrs, all for the last 1'600 hours as of today.

Thank you Dan! Hoping that is what I hear and that is my current plan. I'll probably scope the cylinders at each oil change, doesn't add much time and will add to my data collection and piece of mind.