Over the past few years of instructing and giving checkrides, I’ve discovered what I think is a significant knowledge gap. Let’s say you are a 400-hour instrument/commercial pilot. Chances are, you have never experienced a real-live engine failure (that’s good!). However, when you practice them, the instructor has only ever pulled the throttle back to idle. Up to this point of your training, you have never experienced what a real engine failure looks or sounds like.
The most common reason for an engine failure is fuel exhaustion or starvation. I won’t explain why with this post; I’m just stating that for context. If you ever have an engine failure for one of those reasons, depending on the phase of flight you’re in, you may not notice immediately that you have lost power.
Why Engine Failures Are Harder to Detect Than You Think
Engine failures are harder to detect than most new pilots think. This is due to the windmilling force that continues to rotate the propeller and engine. In fact, it is so hard to detect a failed engine that we use the “dead-foot-dead-engine” method in multi-engine flying to decide which engine has failed. This is because the gauges we typically use for power (RPM and Manifold Pressure) continue to operate almost normally when the engine has failed. Yes, the RPMs will drop, but the MP will not. The MP gauge stays operational since the engine is still turning and creating compression and suction.
What Will NOT Happen During Most Engine Failures
- The propeller will not stop spinning
- The plane does not get “quiet”
- The gauges do not all go to zero
I think the confusion about engine failures has led to more than a few deaths. Many of the fatalities after engine failures are due to the pilot not recognizing the failure and assuming they have a “partial” power loss. Because of this, they delay going to best glide and attempt to fly the airplane back to the field. They let the energy decay more and more and eventually stall/spin.
The Conditioning Problem
Think about engine failures from a conditioning point of view. If you are a 400-hour pilot, you have probably shut down the engine at least 300–350 times. Each time you do this in parking, you pull the mixture knob, and the engine stops. This makes you think that it stops when the engine is starved of fuel.
However, pulling the mixture knob or starving the engine of fuel in flight results in a different outcome due to the windmilling force mentioned above. On the ground, there is no airflow to keep the propeller turning. In flight, the relative wind keeps everything spinning — the prop turns, the engine turns with it, and the gauges continue to show readings that look almost normal.
Hopefully, this post and a good discussion will make pilots think more about what an actual engine failure looks like. The more you understand about how a real failure presents itself, the faster you can recognize it, transition to best glide, and make the decisions that keep you alive.