I reflected on that while ferrying a long-inactive 1993 Piper Super Cub out of Silver City, New Mexico (94E). I’ve bought and sold a few airplanes and learned that it’s rare (or expensive) to find exactly what you want, both getting all your preferences and avoiding all your undesirables. There’s usually an issue or two that makes you pause and test your priorities. With this airplane, the good and the bad was that it had been flown a total of 360 hours. Low time and low stress on the airframe and engine—good, but long periods of inactivity—bad, because that can result in corrosion issues inside the engine. The ideal used airplane has low time but has been flown regularly recently.
I decided to accept the risk of a low-time engine with recent periods of inactivity. I was delighted with everything else about the airplane. Frame, fabric, and interior were exactly as the seller described—almost immaculate, thanks to the dry southwest air where it rested. No damage and complete logbooks since it rolled off the factory floor. This airplane had a great history and good “bones” that I’d feel comfortable flying for a long time while tinkering with upgrades.
My personal observation about the tough and reliable Lycoming O-320 engine on PA–18s is that if they haven’t flown a lot, they often need a top overhaul about halfway to the 2,000-hour time between overhauls. I factored that into my offer, which meant I’d be fine financially if it needed a “top” in the near future—but if it needed a complete overhaul, I’d be behind the value curve. That’s how I assessed and managed the financial risk.
The safety risk was a separate calculation. Even though the airplane hadn’t flown much, the owner kept it in annual, and the cylinder compressions were strong and consistent. He reported no oil burn and clean oil filter inspections—all positive indicators. Still, I’m wary of unused engines. I brought along my borescope, just to have a look. Affordable and easy to use, a borescope reveals a great deal about the condition of the top of an engine. It’s not helpful in inspecting the bottom (crankshaft and other critical pieces), but it’s great for finding cylinder cracks and inspecting pistons, cylinder walls, and valves. Lighted, flexible borescopes are one of the great recent advances in aviation safety.
While the seller assisted, I borescoped the engine and found a suspicious line along the top of a cylinder. Three of four experts I sent the photos to assessed it as carbon flaking, but one—the most experienced Super Cub and Lycoming O-320 A&P I/A in the group—thought it was a cylinder crack. I advised the seller. He offered to pull the jug and if cracked, he’d replace it; if not cracked, he’d reinstall it and I’d pay for the labor. A fair approach. It would take the better part of a day to do the work. I had plenty of time, so that wasn’t a factor, nor was the few hundred dollars it might cost me to remove and replace the cylinder. My biggest concern was the intrusive field maintenance of pulling a cylinder on an engine that showed no other signs of duress and only one of four experts thought might have a crack.
Maintenance actions add risk. Humans make errors, and replacing a cylinder requires substantial work with small details that must be performed to exact specifications. The choice before me was to take the engine as is or take an engine with a cylinder newly installed or replaced in the field by someone I didn’t know.
I decided that—despite the assessment of someone I held a great deal of respect for—with confirmed compressions, no other signs of a crack, no indications of engine duress, and three of four experts believing the cylinder was fine, I would take the engine as is rather than risk intrusive maintenance in the field.
So it was that, at 8,500 feet msl over inhospitable terrain, I found myself reflecting on consequences. Whatever happened, I would be exactly where the confluence of my decisions put me. And I was perfectly OK with that. Such is a part of owning our destiny that is a beautiful imperative in flying.
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