Probably the biggest misconception we hear about flying helicopters is that if the engine fails, we are going to drop like a stone to the ground.
In fact, a ‘forced landing’ in a helicopter can be a very simple thing and in many cases helicopter forced landings are a lot slower and more controlled than the same event in a fixed wing aircraft.
If you’d love to fly in a helicopter but you’re worried about what could happen in an emergency, here’s our beginners guide to what is called an Autorotation. If you’re already familiar with the basic idea, then our in depth article on helicopter autorotations may be the one for you.
If you are new to helicopter flying and would like to know the basic idea of helicopter autorotations, here’s our FAQ that hopefully dispels the top helicopter engine failure myths once and for all!
Here We Go.
But if the engine stops, won’t the blades stop too? No. Imagine riding a bicycle and you stop pushing on the pedals (the engine has stopped) however, the wheels still keep on turning (the rotor blades) and you freewheel along until you run out of energy. The helicopter engine automatically disengages itself from the rotor blades and we, in effect, freewheel.
So how to the blades keep turning if there’s no engine powering them? It’s very, very similar to seeing a sycamore seed gently falling in autumn. The blade of the sycamore seed acts as a ‘brake’ as the air passes upwards through it and slows the seed’s descent. Helicopter blades work the same way. As we descend, the air rushes upwards through the blades, keeps them turning and we use the energy stored in the blades to control our descent and landing.
So, you’re still going down, though. Right? Yes, we’re descending, simply because we no longer have thrust (the engine) providing the blades with lift. However, we are in a controlled descent, not falling like a rock.
So what happens when you reach the ground? As we get closer to the ground, we control our speed using the helicopter controls in the same way that we normally do. Then as we prepare to land, around 50 feet from the ground, we do something called a ‘flare’. If you’ve studied birds landing, especially ducks on a lake, you will see they do the same thing.
We lift the nose of the helicopter, which slows us down, then as we come to a halt, we control the final few feet of the descent with very little forward speed. Next time you’re in the park, study those ducks landing.
But I’ve seen YouTube videos of helicopter crashes, why won’t that happen? Let’s face it, there’s a YouTube video of everything in the world crashing these days, from ocean liners to kids on mountain bikes. Even cats. It seems to be human nature to be attracted to it. Here’s a short YouTube video of helicopter pilot Josh practising autorotations with instructor Oli Nicholls to show how it works. In the video, the engine power has been reduced right down to tickover so its still running but not actually providing any power. Everything you see in the video is simply Josh controlling the helicopter’s descent, without the engine. That is a typical autorotation descent.
What, you actually practice this? Yes we do. All the time. That makes the actions we may need to take in an emergency to be successful, safe and instinctive ones. The overwhelming majority of helicopter pilots will never need to use an autorotation for real. However by practicing regularly, should it ever be needed we have the knowledge and skills practiced and ready to ensure a safe landing.
So, hopefully this dispelled some of the myths and worries people often have about flying helicopters. If you enjoyed this quick blog post and you want to know more about the subject, read our in depth explanation of helicopter autorotations and learn exactly what happens when a pilot flies a helicopter autorotation.
Hi,
Very interesting article. For a book, I am researching how to land a helicopter during autorotation. In my scenario, the pilot attempts an autorotate landing after loss of tail rotor during normal flight. I note that your example videos are over countryside, therefore, plenty of safe landing sites.
If this took place over a populated area, what control does the pilot have for landing location – most of the examples I’ve read, talk about controlling descent, but can the pilot control direction, also?
Thanks
John
Hi John,
The pilot simply controls direction by use of the cyclic like in normal powered flight. Any cyclic inputs may impact RRPM. The main purpose of any turns is to position the aircraft to a suitable landing location and importantly to try and fly the helicopter into the wind in order to reduce the speed over the ground as much as possible.
Over a congested area we have to think carefully about available landing areas should the engine stop (or any other emergency that would require an autorotation such as a tail rotor failure) this might cause us to fly higher or around the said area. What we have to bear in mind is that even during a flare before landing we will still very likely be travelling forward until the ground speed has reduced sufficiently to put the helicopter on the ground. For this reason the landing area can’t be too small.
Hope this helps you,
Let me know if you need anything else.
Oliver