A few issues back, we presented a nicely illustrated article on oil coolers. Many of the pictures came from a visit to a large and popular oil cooler specialty shop on the West Coast—folks who work with coolers every single day for both the certified and Experimental market. In one of those pictures, a technician was installing an oil fitting into a cooler—and wrapping the threads with Teflon tape to seal the joint.
Of course, we received letters on this—because one thing that seems to be taught everywhere in the aviation world is that you shouldn’t use Teflon tape on oil or fuel fittings! This is one of those pieces of wisdom passed down from one mechanic to another, from instructor to student, and documented in a number of books. But here was a respected shop—breaking the “rule.” The obvious question is, “Why?”
That question (Why?) is, in fact, the most important question in aviation—and maybe in life. It is the difference between training a person to do something and educating them in a field. We often teach people to do things by rote (“You do it this way soldier because it has always been done that way!”), showing them a technique that we were shown years before. Yet so very often, we forget to stop and ask why. Knowing the why of a thing is the first and most important part of understanding the thing—and understanding is true learning, something that allows us to grow beyond where we are.
If all you know is how to do a thing, but don’t understand the why, you can never expand on the knowledge, never develop a way to go further, get better performance, fly faster, fly farther. Without the why, we are stuck in our current place—forever. In fact, we—as a society, as a group—are often stuck in one place simply because we don’t understand how to step ahead. And that is usually because we have not walked ourselves through the why.
At KITPLANES, I expect that no one should take what we write as gospel without understanding. I expect our readers to ask “Why?” on everything we do—and therefore, I expect our authors to present the answer within their articles. I am not satisfied with training people to build and fly Experimental aircraft—I want them to learn how to build and fly Experimental aircraft. Experimenting is what we do, and you can’t do that without understanding the big picture.
Aviation, because it grew up so much during the big wars, has always been a place where there was a lot of training and not as much educating. Young men by the thousands had to be trained to build and maintain aircraft in wartime in a few short months—and creativity was not important. This attitude has carried on quite naturally for decades as techniques were handed down from generation to generation. Hangar flying sessions are full of statements about how something is done—but not why it is done that way.
So…why no Teflon tape? It’s not because it doesn’t work as a sealant—in fact, it works quite well. The reason we advise against it is that if you apply it incorrectly (over the end of the fitting), you can cut off a sliver that can plug a small port in a carburetor or fuel servo on a gas line. In an oil system, it can clog a tiny passage and starve a single piston for lubrication. So instead of teaching people how to apply it correctly and carefully, we simply tell people, “Don’t use it!” and don’t give them the whole picture so that they can understand the risks and make their own decisions. If you apply it properly, it is perfectly acceptable—but you have to know how to do it right.
People need to be taught how to make good decisions in Experimental aviation. The books aren’t all written—there are many things that need to be figured out. People want to make changes to a design—but do they know why the design was built the way it was? If not, they might not understand the ramifications of their change. Experimental aviation is a thinking person’s game, and here at KITPLANES, we will always strive to tell you the why. If we don’t, please write us a note.
Paul Dye retired as a Lead Flight Director for NASA’s Human Space Flight program, with 40 years of aerospace experience on everything from Cubs to the space shuttle. An avid homebuilder, he began flying and working on airplanes as a teen, and has experience with a wide range of construction techniques and materials. He flies an RV-8 that he built in 2005, and an RV-3 that he built with his pilot wife. Currently, they are building a Xenos motorglider. A commercially licensed pilot, he has logged over 4800 hours in many different types of aircraft. He consults and collaborates in aerospace operations and flight-testing projects across the country.