As I was working on another post, it dawned on me that I hadn’t finished the story of why I didn’t fly to the Bahamas. As you might recall, in that post I talked about how the ABS service clinic found an anomaly in the cylinder, one that my local mechanic thought was no big deal. To be cautious, I sent the cylinder back to Superior for them to look at it. Then I promptly forgot about it, because I was busy flying to Asheville, Dallas, New Orleans, Atlanta, Auburn, Memphis, and Augusta before I bothered to ask Superior for an update. Turns out the cylinder lining was in fact cracked, but on the inside where the crack wasn’t visible. My precautionary cylinder change turned out to be a necessity, one which saved me the potential for an unpleasant in-flight event and a bunch of additional costs driven by one bad cylinder trying to turn the whole engine into junk.
I noticed that after the cylinder repair, the right engine was leaking small amounts of oil. North Alabama Aviation couldn’t be bothered to try to fix it, so I had Revolution Flight take a look and they identified it as an upside-down gasket installed on the rocker arm cover. This is exactly the kind of small but infuriating maintenance error that every pilot has to learn to deal with. While I could have flown the plane over to Decatur and stormed into the shop to demand that they fix it, I decided instead to write this short note to memorialize their poor performance (along with the ridiculously long time it took them to do the repair in the first place) in hope that future generations will see it when they’re shopping for a maintenance shop.
Back to cylinders. For many engine types, having a cylinder replaced is super common. For example, the large turbocharged TIO-540 used in many models of the Piper Malibu is notorious for requiring frequent cylinder changes because of the operating conditions: the engine’s crammed into a small space with marginal cooling, then operated at high altitudes where turbocharging is used, which increases the heat and pressure regime that the cylinders run under. It’s less common to have to replace them on the normally-aspirated IO-470 engines that my Baron uses, but it’s not uncommon. So far, since the two engines were installed, there have been 3 cylinder changes (out of 12 cylinders total): this cracked one in 2022 and two others back in 2013 or so due to low engine compression. That’s not too bad.
Maybe that’s a good topic for a future post: why cylinders get low compression in the first place, and what you can do about it. Hold that thought…
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