Are engine failures practiced normally? What exactly are the reasons? Is there a particular type of failure that is required training for all pilots worldwide?
From a general aviation standpoint here in the US, yes. Engine out landings and general procedures are practiced during your PPL training. No particular failure is trained for because there are really only 2 situations, the engine is running or the engine is not running. The procedures for different planes vary but generally you set for best glide, pick a touchdown point (airstrip if you can) and head for it. Once in route you can attempt a restart if you can identify the problem and solve it. on some planes you can feather the propellor and such.
That being said that generally applies to single engine planes, in a twin engine plane there are a few more situations depending on the design of the plane. In a twin you may have a "critical engine" as such engine outs are practiced with that in mind and the procedures are adjusted appropriately.
As for the why...
There are lots of things that can take out an engine like a bird strike, a mechanical failure, a fire etc. The fact of the matter is that it does happen all be it not that often, you would be a fool not to prepare.
When I started my training I got curious about piston engines cutting out so I began to ask around. Youtube videos aside, I was only able to actually find one guy who knew a guy that once lost an engine. Engine manufacturing has come a long way since the advent of airplanes and engines are simply more reliable than they once were. Here is a great article that touches on some of the twin engine points about reliability. While it does happen and you should never assume "this wont happen to me" engines are much better than they were 50 years ago when some of the requirements were made for the tests and training standards.
Possible reasons of failure include (in no particular order):
- Running out of fuel
- Not having the fuel turned on - the engine might fail just after you have lifted off - so don't change tanks after your power checks
- Fuel pump failure (many low wing aircraft have two pumps)
- Mechanical failure of the engine
- A propeller blade flying off - you want to stop the engine immediately so that the engine doesn't shake itself out of the aeroplane - if this happened, the aircraft would not be controllable and the end result very bad
- In Flight Engine Fire. Not only would you want to stop the engine, you might like to do an emergency descent, which gets the aircraft on the ground as quickly as possible without excess airspeed
- Ignition system failure that causes either a full power loss or partial (back firing, rough running)
- A passenger touching the throttle or mixture control
- Failure of the exhaust system - leaking exhaust is hot and in the engine compartment could cause a fire or failure.
- Broken throttle cable leaving the engine at the last power setting (could be too high or too low for a safe landing and/or continued flight).
I am sure there are many more. There might be also other reasons such as lack of daylight, bad weather, or a problem with the aircraft where you may prefer to carry out a forced landing in a field.
What you do about a sudden failure depends how close to the ground you are. You must fly the aircraft first - Aviate - Navigate - Communicate. So if the engine fails at 100 feet you must look where you are going and aim to reach the ground under control, even if that means hitting something. Much better than to lose control, stall or spin and hit the ground out of control - this will likely kill you.
If its an engine failure just after take off. Have your own limits as to when it is safe to turn back. Remember you might be turning back into oncoming traffic so its not always the best option even if you do have enough height. My personal limits are that if I have already turned 90 degrees in the circuit and my height is 500 feet AGL or above then I might consider a turn back. This is something you can practice at altitude with an instructor to get it clear in your mind.
If you have enough height, the first thing to see is if the propeller has stopped turning. Airflow will normally keep it turning so if it has stopped the engine might have a mechanical problem that means it will never re-start. If the propeller is still turning, fly the aircraft first and foremost but it is worthwhile memorising the emergency checklist. This might include (from my memory, i.e. not to be relied upon):
Carb Heat - On Mixture - Rich (you may have leaned it out too much and caused a failure, or descended with lean mixture making it even leaner) Fuel Pump - on (maybe the engine driven pump has failed) Change Tanks in case one is empty or blocked Throttle position - check it hasn't vibrated to an idle setting (your hand should be on the throttle during take off to prevent this) Magnetos - maybe one has failed the engine may run well on one or the other.
Don't forget your pre landing checks if it still doesn't start!
When you get closer to the ground close the throttle and forget about it - your attention must be flying the aircraft and landing as safely as possible.
Flying a twin is harder, because you must learn how to fly it on one engine safely (it will pull one way or another) and this takes experience and currency. Otherwise, rather than you flying the aircraft, the live engine will take you to the scene of the accident. Many twins have single engine safety airspeeds (blue line) which if you go below, you cannot have the live engine on full power otherwise you will lose control due to lack of airflow over the control surfaces.
Some pilots don't touch the engine controls after takeoff until at 500 feet, because there is a slightly increased chance of failure if you do change the power setting for example, or pull the mixture instead of the throttle.
A difficult situation can be one where the engine is producing partial power - not quite enough to fly with. You might be tempted to try so you can reach an airport rather than land in a field.
Despite writing all this I feel sure I have missed something, hope this helps anyway.
The question of engine failure in Single Engine, Fixed Wing, Piston Engine, Factory Built (SE FW PE FB) aircraft is one where myth overtakes reality.
A quick look at the NTSB.gov website (publications, annual reviews) shows that engine failure from mechanical issues ranks from first to third as the cause of GA accidents in every year since the summary stats were first posted.
Having experienced three engine failures in about 4,000 of flying SE FW PE FB I began to wonder about just how reliable my engine really was. My engine failures were in three separate engines, three different aircraft, and included one catastrophic failure and two partial power loss events.
All were mechanical failures traceable to maintenance. None show up in the NTSB data base because all had a happy ending (no injury, no damage, no requirement to report - and therefore invisible to the 'official' tally of engine failures).
In 2014, after my catastrophic engine failure I put together a survey which was posted on several forums and sent to several flight schools. Six questions asked about total pilot time, logged hours in SE FW PE FB aircraft, loss of power events (both partial and complete loss), and a brief optional narrative of any loss of power event.
At this time I have about 760 responses. FWIW, a very impressive number of pilots have experienced one or more engine failure. Overall, considering both those who have not (yet) experienced loss of power from any reason, about 10% of all participating pilots have experienced loss of power that required early termination of flight, but only 2-4% of all pilots, more or less, reported an accident where the NTSB required notification.
Of course, the probability one will have an engine failure is related to exposure. Higher time pilots tend to have more loss of power events. These data suggest to me that the total number of engine failures in SE FW PE FB aircraft are substantially higher than the NTSB data would suggest... In other words, data shows there is a myth of piston engine reliability.
Practice for engine failure (from any cause!). You might need those skills.