It's the situation you always feared and banned from your head before you entered the airplane; an engine failure. Although it's a rare phenomenon, it still occurs. Most engine failures occur at multi-engine aircraft. It is said that multi-engine flying is safer than flying on a single engine, but that's not absolutely true. Of course, in theory it should be, but in real life there are more incidents and, unfortunately, accidents, where multi-engine aircraft are involved. In this article we will primarily discuss engine failures on multi-engine aircraft, because there isn't as much you can do when your single-engine fails. We'll discuss some actions that cause engine failures and I'll give you advice how to avoid those actions and how to handle an engine failure.
What causes an engine failure to occur? There are several reasons, but the most common reason is an empty fuel tank. Many airplanes, like a Cessna 172/182, have just two tanks and a fuel tank selector that can select either the left tank or the right tank, but not both. If you forget to switch to the other tank about every 15 minutes, then a growing imbalance will usually let you know that there's something wrong. If you don't act positively at that point, the engine(s) will simply starve of fuel.

Everything still under control; EGT, CHT, oil pressure and temperature normal.

When you do your walk around the airplane, you should always check the cowl flaps and the engine intakes. Cool air needs to be transported through the engine when it's running so that it keeps running and so that it stays cool. Anything that's in the way of the air should be removed (but leave the engine compartments where they are). Verify that you can open and close the cowl flaps. In the climb, your speed is low and your engine is running at max RPM; not a good combination. Therefore, keep the cowl flaps open so that the air can circulate through the engine and cool it down. Monitor CHT, EGT and oil temperatures at takeoff and during the climb. High CHT temperatures can cause detonation and pre-ignition, two situations that usually cause a complete engine failure by destroying the pistons.
In the cruise, your speed is usually high enough to cool the engine and therefore the cowl flaps can be closed during cruise. When descending, you're also at high speed but thrust is usually at or near idle. Now it's necessary to keep the cowl flaps closed, because there's a risk of engine intake icing and carburettor icing, and that's of course another thing you don't want. When you suddenly see oil pressure decreasing and oil temperatures increasing, then you might have an oil leak. You'll have to shut down the appropriate engine to prevent overheating and engine fire.
How can you know an engine failure has occurred? The very first sign of an engine failure is the yaw. The windmilling propeller significantly increases drag on that wing, so the airplane's nose yaws to the failed engine. You can feel this when flying in VMC, or look at the inclinometer; the ball will be on the side of the life engine, since you are slipping. When an engine has failed, the EGT will decrease fast and RPM will stay at around 1500. Oil pressure and temperature decrease slower.

Engine failure! Watch the inclinometer, fuel flow, oil temperature, CHT and EGT. We've just verified that engine 1 has failed.

How to handle an engine failure? Your first reaction must be to counteract the yaw with opposite rudder. If you cannot counteract the yaw with you feet, then the only solution is to decrease the power on the live engine. Remember that in real life there's a great pressure on the rudder panel, since the airplane has to be steered using only your feet and a few meters of steel cable. After you've neutralised the yaw, verify which engine has failed and feather it. Also close the throttle in case in suddenly comes back to life again. When you're far away from an airport, you may want to crossfeed the engines to reduce the imbalance. Don't use crossfeed when taking off or landing! Use trim to keep the airplane straight (elevator, rudder and even aileron trim when required). And finally, nurse the live engine; she has to take you back to the safe Mother Earth!

We've got control back; coordination ball centered again, left engine feathered, left RPM at zero (confirmed feathered), left CHT, EGT, oil pressure and temperature zero. Slight rudder trim to counteract the remaining yaw.

When an engine fails while you are taking off, you want to you use all the power available from the live engine. Climb performance reduces by nearly 80%, so, in case of our Baron, which can normally climb at 1000 - 2000 fpm, it's just 200 - 400 fpm! That's really not very much. And we can only achieve that when we fully use the live engine in the right way. An engine failure after takeoff (EFATO) is therefore the worst moment for an engine failure to occur since you're slow, flaps and gear may be still down, flight controls are still a bit sloppy. When an EFATO occurs, you should first counteract the yaw with rudder, and then bank to a maximum of 5 degrees to the live engine. This is how you get the most out of the live engine. When climbing, cruising, descending or on approach, just the rudder will be sufficient and no bank is required. After the failure, keep an eye on your ammeter, since you've lost one alternator. Same applies to you vacuum pumps when flying in IMC; you've only got one left.

So, are multi-engine aircraft safer than single-engine aircraft ? That fully depends on the pilot. If he or she is current and knows what to do when an engine failure occurs, then yes, multi-engine flying is safer. But if not, then there's no difference between single- or multi-engine flying.
Remember, an engine is just like a human; it needs air and water (well, fuel) to stay alive. Make sure it gets those things, and it'll do everything you command him to.

Happy landings, or better, happy takeoffs!

Only to be used for flight simulation purposes. No responsibility taken for real life accidents.

| 15.05.2006 | Read more | Print |