Lucky pilot

[Ragwing nut]

This would be early 2000's maybe late 90's

[astjp2]

I think this illustrates the importance of maintaining a clean engine.

It can be seen even in the photos that this cylinder was cracked (up to 50% or more of the circumference) for quite some time prior to the final failure. The oil and soot buildup on the intake components and ignition wires below the cylinder is a telltail sign that the cylinder has been blowing oil and hot gases for a while.

Keep your engine clean and free of oil leaks and you'll see an impending failure before it develops this far. Just my opinion of course

Actually Scott, the crank seal was leaking and was changed a couple of hours prior to the failure, that failure would not have put oil on the engine, even flying back it did not spray hardly any oil. I was mainly limited to the combustion chamber, even the pushrod tubes were still sealed surprisingly.

[astjp2]

how old was that cylinder? There was a batch of superior cylinders that the barrels were not deburred correctly and popped a few heads. I think there is an old AD on it.

that ad was only for lycoming and big continentals.

[Ragwing nut]

that ad was only for lycoming and big continentals.

We had some O-300 cylinders here that was like that superior had to warranty.

[astjp2]

We had some O-300 cylinders here that was like that superior had to warranty.

I wonder why it seems that I have only heard of O-300 failures and not 200? This is the first one I have actually seen in person. How many have you seen Mike? Tim

[Scott]

Pushrods tubes on the failed and adjacent cylinder, ignition wires and the tyraps that strap them to the intake, intake couplings and breez clamps, intake elbow on the adjacent cylinder, lifter housings, all look soaked with black grunge to me. It might be argued that what I see could have come from anything leaking in that area. The point is however that a crack like that will reveal itself if the engine is otherwise leak free and clean.

Oil between the fins in the vicinity of the cylinder-to-head joint is always cause for concern, but if everything is soaked and dirty how will you know. It's not going to show up during a compression test because the piston at tdc is beyond the crack. Oil leaking is your best hope of catching this before the catastrophic failure.

[Ragwing nut]

I wonder why it seems that I have only heard of O-300 failures and not 200? This is the first one I have actually seen in person. How many have you seen Mike? Tim

popped heads? not many on small continentals. More than my fair share of stuck valves. And on the O-300 we caught it at installation. they were so screwed up we hung a rag at the top of the barrel when we were cleaning them prior to install.

[astjp2]

New?

[Ragwing nut]

New?

yes

[Guest]

Pushrods tubes on the failed and adjacent cylinder, ignition wires and the tyraps that strap them to the intake, intake couplings and breez clamps, intake elbow on the adjacent cylinder, lifter housings, all look soaked with black grunge to me. It might be argued that what I see could have come from anything leaking in that area. The point is however that a crack like that will reveal itself if the engine is otherwise leak free and clean.

Oil between the fins in the vicinity of the cylinder-to-head joint is always cause for concern, but if everything is soaked and dirty how will you know. It's not going to show up during a compression test because the piston at tdc is beyond the crack. Oil leaking is your best hope of catching this before the catastrophic failure.

got it, thanks, Dave R

[Scott]

Actually Scott, the crank seal was leaking and was changed a couple of hours prior to the failure, that failure would not have put oil on the engine, even flying back it did not spray hardly any oil. I was mainly limited to the combustion chamber, even the pushrod tubes were still sealed surprisingly.

I guess these things are relative... we grow accustom to seeing oily grimy aircraft engines and it's easy for us to accept it as normal. I have a problem in that I cannot tolerate oil leaks, dirty engines or dirty cowlings. Even the British motorcycles I rebuilt when I was young didn't leak oil! A drop of oil in the cowling of my airplane is cause for investigation. I may not fix it right away, but I'm going to find out where it's coming from. Of course I have the luxury of not having to explain my hours as I'm my only customer these days.

Anyway, here's what I see in the photo that suggests to me that if the engine had been otherwise clean and dry, the fatigue crack in that cylinder would have revealed itself reasonably clearly. While the area between the fins is not readily visible, there is evidence in this photo of liquid oil draining from the crack. Again, impossible to notice if the engine is otherwise generally wet with oil and grime, but if the engine is normally clean and dry.....

[Guest]

Good illustration, thanks. I never understand why we want to paint things black on airplanes and hide the clues and cracks.

[Scott]

One reason to like the original alodine (gold) conversion coating that continental did on the cylinder heads.