Building an Airplane Engine

Kit build airplanes are nothing new any more, but how often do you hear about building the powerplant for it as well? I found out that you can do just that at Superior Air Parts Build School. I learned about this workshop after I had settled on using their XP400 engine in the Glasair Sportsman I’ll be building. So when I realized I could build the very engine going in the plane, I just couldn’t pass up the opportunity. Although it sounds like a recipe for a looming disaster, they convinced me that yes, a non-A&P, rank amateur like me could do it.

The Build School is a three-day workshop that takes place at Superior’s factory in Coppell, Texas, near Dallas, conveniently located only a short hop from the Dallas-Fort Worth airport. The Superior staff is hospitable and very welcoming, which made for a relaxed and enjoyable session. While they can accommodate as many as four in a class, I was the only one attending this session. That was quite fortuitous because the whole time, the master mechanic, Darrell Ingle, was 100% focused on this project. It felt like I was in a master-apprentice arrangement.

The build process starts from a cart of parts – nuts, bolts, washers, gaskets, cam shaft, crankshaft, pushrods, cylinders, rings, lifters, and so on. Under Darrell’s direct supervision, we systematically assembled the engine, following each of the exact same build steps and quality assurance inspections as their factory built models. (Below are time-lapse videos of the build that I managed to create on days two and three using a new iPad app I found.) While some one-time tricky operations or specialty skills, like grinding and gapping the piston rings, were better left to the expert’s deft touch, on most repeated operations, I was shown how to do the first one, then turned loose to do the others. By the end I had installed seals, gaskets, cylinders, intake pipes, valve lifters, magnetos, the starter, and even fuel lines and injectors. All that remained after I left Texas was for them to hook up a few remaining parts after they test the engine on the dynamometer. Once it all checks out, it will get crated and shipped to Glasair’s factory at Arlington Airport, Washington.

Although this workshop by no means qualified me to tear down and rebuild an engine, it did remove any mystique surrounding its assembly. While the process certainly requires absolute attention to small details of torquing bolts, checking and adjusting clearances, even orienting washers correctly, it is fundamentally quite straightforward. The inherent simplicity harkens back to earlier days tinkering with car engines. I remember in high school helping a grease monkey friend put together his V-8 engine that was in pieces on the garage floor. Nowadays though, the complexity of auto engines often requires computer connections, software, and specialized knowledge just to troubleshoot. Not nearly so with these aircraft engines. Added complexity would mean more failure opportunities, so reciprocating aircraft engines usually have only the most basic and time-tested systems. And aircraft buyers can often be real Luddites as well. I even saw one brand new carbureted engine in the factory getting ready for delivery. Imagine that!

Besides the assembly process, there is something intangible about holding and examining each part individually, and then seeing them all go together. I don’t know how valuable it is to know where the propeller governor is on this engine and what it looks like on the inside, but it just feels better knowing it. There is nothing magic about the roller lifters, but they sure are interesting to see and install. Tracing the flow of oil through the various parts all the way back to the sump was fascinating (I hadn’t realized that the push rods have a small oil channel). It must be my inner nerd talking.

I’m a long way and many tools shy of doing major aircraft engine work, but after the workshop I do feel better prepared to own and properly maintain it. I expect that having had the opportunity to quiz the instructor on the various pieces, how to maintain them, the typical causes of failures, what to look for and where to look when inspecting the engine will all prove valuable later on. And I should know exactly what the shop is talking about when the need arises to have some work done on it. At the very least, I can certainly change the oil with confidence now.