Engine Failures Happen

By Mark Murray, EAA 394554

This piece originally ran in the August 2023 issue of EAA Sport Aviation magazine.

I don’t mind an engine that fails on rare occasion. Before you send a psychiatrist my way, please let me explain.

Like so many others, my entry into aviation was through a typical general aviation trainer — a Cessna 150, in my case. And, like we’ve come to expect, the little Continental O-200 pounded away just fine for those hours. After a session of practicing engine failure simulations, I asked my instructor — an experienced, high-time pilot — if he’d ever experienced a real failure. He’d once experienced a flameout in a private jet at altitude but was able to restart the engine without trouble.

In contrast, now 30 years and almost 2,000 hours later, I’ve had more than my share.

I don’t exactly welcome engine failures, but why my opening statement? First, let me explain my experiences and what I’ve learned.

Experience Is a Hard Teacher

It’s easy to say, “Hey, you’re flying glorified snowmobile engines around. What do you expect?” But, in prepping this article, I reviewed my failures. The results are interesting. The majority are fuel delivery related (no, not a lack of fuel onboard, but problems with either fuel hoses or filters). Most were early on when I was first learning how to operate and maintain my airplane. Or, in other cases, they were friends’ airplanes, and maintenance was insufficient or lacking altogether.


When people disparage two-strokes as far as reliability, it’s usually because of the engine’s early history of sudden failures without much warning. They will commonly refer to the engine “seizing,” which describes when the piston almost instantly stops in the cylinder, usually trading metal in the process.

I can honestly say that in more than 1,500 hours of two-stroke experience, I’ve never had that type of seizure. I came close once, when I failed to completely warm up a Rotax 582. On this particularly cold winter day, the cylinder couldn’t handle the rapidly expanding piston as I climbed out on full power. There was a slight stumble, but the engine kept right on running. A teardown showed evidence of “shock” type damage to the piston. Completely avoidable if I’d warmed up sufficiently, and if anything, an indicator of reliability; it continued to run even after improper operation.

Sometimes the failures resulted in a complete power loss, sometimes in a partial power loss, and sometimes in simply a precautionary landing with no sustained power loss. I once had this type of problem in a special light-sport aircraft. As a factory-built airplane, as opposed to a kitbuilt airplane, you’d think that you’re operating something with a little more “built-in” reliability. Not necessarily.

A heavy band clamp went through the prop shortly after takeoff, taking out a considerable chunk of it. The vibration was significant. Fortunately, everything stayed intact, and we were able to land without incident. And, it was four-stroke powered, by the way.

Let’s face it, sometimes no matter what you do, mistakes will happen. No one is perfect. I once had the crankshaft completely lock up without warning on an engine with about 40 hours. It was a bad crank bearing. In another instance a clean fuel filter stopped up. It looked perfect to the naked eye. Only when it was disassembled and inspected closely under a bright light could you see the contamination.


What Did I Learn?

Maintenance and Operation: You can’t learn too much. Early on, I figured that I could keep an airplane engine running. After all, I kept plenty of other types of engines maintained. Even as deceptively simple as most airplane systems are, there are hidden dangers. I learned by experience and by reading. The research was great, but I should have sought out more advice from experienced flyers.

By the way, make sure the advice you’re receiving is from someone actively flying with lots of time behind whatever engine you’re running. A lot of aviation-oriented folks are friendly and ready to help out, but their experience may be based on just a handful of hours. Almost anyone can keep an engine running for a few hours.

Fuel systems: Keep it simple, and use quality parts. Resist the temptation to reinvent the wheel in an effort to make the system failure proof. Many times, so-called improvements have unintended failures built in that won’t be readily apparent. There’s a good chance that the kit manufacturer designed a reliable system; failures typically don’t sell well. If the system has been updated or modified by builders over the years, take the time to understand the reasons behind it. There may be good reason for the update. Sometimes it was for increased capacity, and maintaining reliability will require more effort on your part.

Also, I’m reminded of the “series” fuel system versus “parallel” fuel system debate. The idea is that running two completely separate fuel delivery systems in parallel is safer. Possibly, but is the additional complexity worth the additional maintenance to keep it safe? Is the parallel system fully tested?

The old adage “An ounce of prevention is worth a pound of cure” is appropriate here. My experience is that simple, well-maintained systems using quality components is the way to go. By the way, I’ve also learned that thinking of your fuel system filter as a “secondary” filter helps, too. By that, I mean you’ve already prescreened the fuel before it entered your tank (portable fuel cans are notorious for collecting water and garbage). Funnels with built-in screens and sumps are commercially available for this purpose. And don’t forget to drain and clean your airplane fuel tank often. I clean mine every 100 hours or once per year, whichever comes first. Even with prescreening the fuel, contamination still occurs.

Train and then practice: In your primary training, you no doubt practiced engine failure simulations. That shouldn’t have been the last time you did so. Continue practicing. “Spot” landings are great for this. Pick a well-defined spot on a lonely runway, cut to idle on downwind once the spot is off your wing, and see how close you can get. I typically pick the third centerline dash from the numbers, but any spot will do if you can easily see it from altitude. And make sure to give yourself an out in case your practice dead-stick turns into the real deal. Typically, this means that the runway is at least partially surrounded by open fields.

Never use the numbers as your “spot.” The last thing you want is to apply power just after realizing you won’t make the numbers, only to learn that power is no longer available. Obviously, some airports will be better suited than others for this practice.

The idea is to get to the point where you know what you and your airplane are capable of. There’s no way of knowing exactly what the conditions will be of your next failure. Altitude, winds, full or partial failure; who knows? But getting to the point where you can nail that spot every time will be a huge advantage. But only if you stay proficient at it.

Be wary of strange airplanes: Your buddy might be the best guy in the world, but he may not maintain his airplane as much as he should. When I was younger and dumber, I jumped at the chance to gain new skills in different designs. In a way, it was good experience, but sometimes it was more experience than I bargained for.

Never become complacent: I teach my students to always keep on the lookout for potential landing zones. Once, I was asked, “How do you find enjoyment in flight if you’re always concerned with engine failures?” I use the example of driving on an interstate highway. You have to be alert to traffic all around you and to the potential of merging traffic. However, you can also enjoy listening to the radio or having a conversation with a passenger. Once you get over the fear of engine failures, you’ll find that you can plan for them and enjoy flight at the same time.

What constitutes an acceptable emergency landing zone depends entirely on where you are, how high you are, conditions, and what you’re flying. I once experienced a complete failure on takeoff in a friend’s T-bird ultralight. There was water in the fuel. From full throttle to almost instant failure in less than 10 seconds. It was a 700-foot strip with short pine trees off the departure end. Fortunately, I heard my instructor’s voice in my memory, telling me to force the nose down. All the more important in a high thrust-line pusher. The young, rubbery pines kind of acted like the plastic bristles of a hair brush. From initial touchdown to stopping was only 90 feet. Amazingly, there was practically no damage to the airplane. There’s a lot to be said for the low kinetic energy of our little machines.

On another occasion, a broken fuel hose in a friend’s Challenger caused a partial failure on takeoff. The engine would surge and then falter as it was starved for fuel. I was maybe 300 to 400 feet up, with a passenger. With nothing but tall trees ahead, I both dove and banked hard to the left, toward an open field. The Challenger demands almost constant rudder work to remain coordinated, and this turn was no different. It quickly became apparent that I still had plenty of altitude to make the runway, so the turn was continued. Now, just to the right of the runway numbers, I was high and fast. A hard slip had us touching down at about the midpoint of a 3,000-foot runway.

All Airplanes Are Gliders First

An experienced pilot once told me that he was no longer afraid of engine failures. I thought he was nuts. But now, I get it. Being acutely aware it’s possible, yet usually recoverable, gives you that. I’ve learned the wisdom of the saying “Never fly over something you’re not willing to land on.” Strangely, it’s given me a lot of appreciation for the “spare” motor we always carry around with us: gravity. If that seems like a strange comment, take some glider lessons. It’s amazing to see what’s possible when both aerodynamics and energy management are used together.

So, hopefully you understand my initial comment a little better now. If you still want to send a doctor my way, no worries. I’m sure he’ll find something to do.

Mark Murray, EAA 394554, of Georgetown, Georgia, was always fascinated by airplanes. He discovered ultralights thanks to an article published in National Geographic in 1983. In 2008, he earned his light-sport repairman maintenance rating and turned his hobby into a business, eventually becoming a CFI and an A&P mechanic.