Mayday, Mayday, Mayday!: How To Handle a Quadcopter Engine Failure In Flight

Written by Andre Louis-Ferdinand

In this article, the first of this article series "Mayday, Mayday, Mayday!:", I will talk about engine failure in flight and how to land safely. Let me be clear here, I am talking about a single engine failure, not complete power loss, such as when the battery becomes unseated in flight. In that case, you are about to feel very helpless as you watch your aircraft quickly fall to the ground.

With a single engine failure, loss of lift isn't your problem unless you are sling loading (carrying a lot of weight from a tow line). The real issue here is aerodynamics; your drone will most likely not be able to maintain complete control with only three of the rotors spinning. What will most likely happen is the drone will want to immediately flip into the direction of the damaged engine. Remember, it won't try and dip in that direction, but actually flip, which is much faster and scarier. What you do is IMMEDIATELY descend as quickly as possible and move the directional control in the opposite direction of the damaged engine.

Having one less engine, you will fall the ground like a rock. Your UA will start to wobble a bit due to VRS (Vortex Ring State), but having one less engine will help you out here because you will have less downward thrust. When you are about five feet from the ground, increase thrust to around 50% and keep the directional control in the opposite direction of the engine failure. With a fair amount of luck, you will land the drone with a slight skid in the direction you had the directional control pinned to. At the very least, you will have mitigated the damage to your drone significantly.

While this seems simple, in actuality it is not. Obviously, you won't be expecting the shit to hit the fan until it does and you also won't easily know what engine has just failed. However, I recommend you practice the motions at home with your controller turned off so the muscle memory is there when you need it. While testing this out myself, I was able to successfully land the aircraft all three times I tried it. However, landing one was a little "sketchy" and almost resulted in a flip when I entered the fall.