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Twins - engine failure / EFATO (merged)

AeroPlus wrote:

a short period of less than a minute

Much, much less than a minute. Ten to fifteen seconds, I would say.

Isn’t this an argument that we could just put on autoplay and walk away, together with iPads vs Android, PC vs Apple, Brexit vs Remain, Protestantism vs Catholicism etc?

There are some people who are completely convinced that twins are death traps, and others who consider being airborne with one engine an emergency. We know their arguments. The mainstream know that they are both wrong and that the truth is nuanced and lies between, but we’ll never convince them. Do we need to rehearse the arguments endlessly?

EGKB Biggin Hill

Timothy wrote:

There are some people who are completely convinced that twins are death traps, and others who consider being airborne with one engine an emergency. We know their arguments. The mainstream know that they are both wrong and that the truth is nuanced and lies between, but we’ll never convince them. Do we need to rehearse the arguments endlessly?

I suppose we do because it is a reflection of those who havent flown twins so as I indicated in the last post, are convinced by the often repeated stats., without having an understanding of why the numbers are what they are. It is worth repeating because some will be convinced, and will go on to get their multi rating and for those who would otherwise aspire to and are capable of multi flying this is a good thing, because it will make for better pilots.

Timothy wrote:

The mainstream know that they are both wrong and that the truth is nuanced and lies between, but we’ll never convince them. Do we need to rehearse the arguments endlessly

’t is the way of the world these days. Polarised opinions, mostly ill-informed on both extremes, dominate the debate, and very rarely is anyone of these going to change their opinion.

However, the somewhat quieter ones in the middle listen and learn, and it is for their benefit, not the extremist’s, we need to continue to point out the trade-offs.

The trade off here is quite simple.

  • A twin allows you to fly certain missions with a higher margin of safety (night, low IFR, long overwater legs)
  • This comes at the expense of increasing risk in other operations (mostly take-off).

Whether that increases your overall risk depends on the mission profile, and how well the individual pilot mitigate this risk through training (and not flying Seminoles).

So everyone is right. The low-hours nice-weather day-time bimbler is safer in a single than in a twin. The as-near-as-it-gets-all-weather traveller with matching training is safer in a twin. Everybody in the middle needs to decide for himself.

Biggin Hill

On this topic, I like this article:

http://www.cfidarren.com/p8740-25.pdf local copy

Home runway, in central Ontario, Canada, Canada

In my opinion the reasons for many people flatly rejecting twins are twofold:

- not being able to afford to operate one (sour grapes)
- being scared to death by the horror stories which in most cases are invented by people who never have flown a twin.

In the light twins GA usually uses, there is no reason why people should have V-mc accidents on take off, the options are pretty straightforward: Anything happens before you are cleaned up and at a reasonable height it is land straight ahead like in a SEP. Once you have altitude and are claned up, then you handle it according to training and procedures. Yes, this requires recurrent training, yes it requires skill, but I refuse to accept that a reasonably trained pilot can not handle these.

What would make a lot of sense is the much increased use of high fidelity flight simulation for training such things. It has rightly been said that there is a heightened risk in training OEI scenarios in the real airplane apart from technical aspects as engine shock cooling e.t.c. Apart there are things you simply can’t do on the airplane but which are quite instructive to demonstrate in a good sim. Recurrent training of these scenarios in high fidelity sims should be well suited to iron out common mistakes and misconceptions and to instill automatisms and instincts necessary. It also allows to demonstrate a lot of things you can’t safely demonstrate in the air.

I openly admit that I can’t afford to fly a twin but if I could it would be an absolute no brainer.

LSZH(work) LSZF (GA base), Switzerland

Let me check my understanding: you can “safely operate a twin bellow VMC on one engine” by shutting down or reducing power on the good engine? or there is something wrong here? so at the end you get something like a single but the cost is the high MTOW if you mess up on take-off !

If you meet a guy with polarized opinion just ask him which one he would choose a heavy SEP and a light MEP?

For en-route (water, weather, night), the comparison is worthless as we tend ignore the change in mission profile when one operates a twin

IMO, the overall safety stays the same as given by pilot risk appetite than aircraft = mission: flying in icing with a FIKI is the same as flying in clear air in a non-FIKI: the FIKI guy is well prepared for non expected ice encounter in clear air but he has more things to go wrong as he tends to stay a lot in the soup…

Last Edited by Ibra at 26 Apr 14:53
Paris/Essex, France/UK, United Kingdom

I could buy a DA42 if I wanted one. So why don’t I?

  • large airframe; would have loads of trouble hangaring it at Shoreham
  • FTO training for ME
  • 1 × PPL ME test, 1 x IR ME test, 1 × FAA CPL ME test, 1 × FAA IR ME test (last two would fill me with dread, given the options)
  • hard to do the tightly managed maintenance I now have so well organised

and I am sure I am not the only one who has been up this path, because lots of people pay more for an SR22 than you could get a DA42 for. OTOH a DA42 (or any other twin) doesn’t have a chute, and the biggest “wife concern” is not an engine failing but the husband getting a heart attack.

I would have said a few years ago that if I was living in Greece I would definitely have a Jet A1 burner, but now most of the airports which have that and don’t have avgas have been Fraported so I would be paying 300-400 each time.

ME EFATOs etc would not feature in my assessment, probably wrongly

And the cost per mile of a DA42 is same as the TB20 in the UK (diesel is fully taxed here except when used for “training”) and about half of the TB20 outside the UK. I do think the maintenance would be a lot more than the ~1k I currently spend however, on scheduled maintenance parts, due to Diamond owning a lot of the parts supply.

As to why twins largely died out, we did this before. And that happened pretty well long before Cirrus offered the chute. The main reasons were ME pilot paper maintenance, and avgas cost. That made twins unattractive to rent, and when that happened very few people went on to buy one.

Administrator
Shoreham EGKA, United Kingdom

Ibra wrote:

Let me check my understanding: you can “safely operate a twin bellow VMC on one engine” by shutting down or reducing power on the good engine? or there is something wrong here? so at the end you get something like a single but the cost is the high MTOW if you mess up on take-off !

If you are below Vmc and one engine fails, depending on your altitude, counter the yaw, lower the nose and yes, possibly reduce power on the good engine until you get over Vmc. Then you can increase it again, staying above Vmc all the time or mostly blue line if you need to climb.

At take off, rotation speed should be over Vmc and usually is. Only in particular situations such as short field ops, it is possible to lift off before Vmc. In which case, if an engine fails, you reduce power on both engines and land straight ahead like in a SEP.

Pretty much the same goes if you take off normally (Vr>Vmc) in low powered twins and still have the gear or flaps extended in those low powered airplanes, your safest option is mostly to close both throttles and land straight ahead as you would in a SEP. That is maybe the first 15 to 20 seconds after lift off.

Thereafter, iif an engine fails once gear and flaps are up, you maintain blue line speed and proceed to identify and feather feather the dead engine. Then you climb at Blue Line speed until safe altitude and consider your options.

But it has to be stressed, these are procedures which concern the first few minutes of flight. After that, an engine failure or shutdown is a very different story. As soon as you have altitude to trade to maintain speed and to identify what is going on, the twin will be much less of a challenge. Clearly, the principle of identify, (if possible rectify) and feather/shut down is still done quite expeditiously, but you have more time than if you are just a few feet above ground.

The same goes for a go around, which is maybe the most critical scenario, if an engine fails during power application. If power is applied reasonably slowly as it should be in most engines, you again will have a chance to catch an approach to Vmc (which you should be well above in any approach) and maintain control, even if that means that the 2nd engine can not initially be run at full power. If you can’t arrest the rate of descent you will have to land, but the most important bit is to maintain control. If it fails after you are cleaned up already, the procedure will be the same as after take off at safe hight.

It sounds much more complex than it is. I would suggest you try it out in a good twin sim once and see how it’s done. Then things become much clearer.

LSZH(work) LSZF (GA base), Switzerland

Peter wrote:

I could buy a DA42 if I wanted one. So why don’t I? large airframe; would have loads of trouble hangaring it at Shoreham FTO training for ME 1 × PPL ME test, 1 x IR ME test, 1 × FAA CPL ME test, 1 × FAA IR ME test (last two would fill me with dread, given the options) hard to do the tightly managed maintenance I now have so well organised

I think cost is the only reason for not doing so.

Even cost can be dubious in some circumstances because although the running costs are more, the capital outlay might be less, comparing say a good low hours twin with a new SEP.

Everything else is doable without much hassle.

I dont think a DA42 is a good solution, other than the Jet A1 solution. Twins should be about performance, load carrying, all weather capability, stability and comfort. The DA42 doesnt tick many of those boxes, although they are enjoyable to fly.

As one example there are many twins you can throw as much in as you like, and four adults, you cant do that with many SEPs.

As to that critical departure, I suspect power is the key. Some of the underpowered twins it seems to me where never ideal or a sane compromise, with others even climbing away on one is not the event it is often made out to be as others have said.

Anyone who wishes to be a “better” pilot should at least complete their MEP, as much as a tail wheel or some aeros assuming you have the time and cash. You will learn new skills and you will be a much better pilot in consequence. Afterwards flying almost any SEP seems a complete non event for some reason. I would recommend it.

The market has spoken for GA. Singles are the winners. And in no small part thanks to Cirrus chute design – this has given confidence to nervous fliers, wives and husbands alike. But, we are also taken back to the shed and slightly violated by singles – they’ve somehow managed to convince all and sundry that a TBM 940 that costs $5 million is “much cheaper” to operate than a turbine twin. But because there are more SEL pilots than MEL’s, that’s what gets passed around.

I’m hoping electric propulsion will in due time eliminate these factions and even the SE vs ME think. In an electric world, there is almost no penalty for adding motors. Just like in Nasa’s testbed, you’ll probably see multiple smaller propeller along the whole leading edge and vectored thrust. We’re all be safer fore it and we will all spend less money. Everyone wins.

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