Why are multiple engines different?

Why is flying a multiengine aircraft a separate certification from the
basic license (if I understand correctly)? What is so different about
having more than one engine that justifies a separate certification?
Apart from a few procedures for the failure of an engine, isn't
everything else pretty much the same?

Does this mean that it is not possible to study for an initial license
in a twin-engine plane?

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Mxsmanic wrote:
Why is flying a multiengine aircraft a separate certification from the
basic license (if I understand correctly)? What is so different about
having more than one engine that justifies a separate certification?
Apart from a few procedures for the failure of an engine, isn't
everything else pretty much the same?

Does this mean that it is not possible to study for an initial license
in a twin-engine plane?

Complexity. Flight dynamics are different and the systems are more complex.
You can get a AMEL first. But why?

Michelle P

Michelle P writes:

Complexity. Flight dynamics are different and the systems are more complex.
You can get a AMEL first. But why?

Mainly for the purpose of flying the same multiengine plane I fly in
simulation (a Baron 58). Of course, this aircraft costs almost two
million dollars, but if I can fantasize about having enough money for
a license, I can just as easily fantasize about having enough money to
buy a decent aircraft.

Anyway, I dislike P-factor and torque issues, and I figure they'd be
less prominent on a multiengine aircraft (especially with
counterrotating powerplants, but apparently there aren't many aircraft
like that). And I could limp home on one engine, whereas I'd be out
of luck in a single-engine plane. Given how frequently piston engines
fail, that seems like an important consideration.

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"Mxsmanic" wrote in message .

Anyway, I dislike P-factor and torque issues, and I figure they'd be
less prominent on a multiengine aircraft (especially with
counterrotating powerplants, but apparently there aren't many aircraft
like that). And I could limp home on one engine, whereas I'd be out
of luck in a single-engine plane.

And the above, my friend, shows precisely why separate training and
certification are required. Any airplane, from Cessna to Boeing, is fairly
easy to fly when everything goes right. Teaching the procedures involved in
an engine failure is fairly straightforward; and, like most straightforward
procedures, they are not difficult to learn with practice. But the rub
comes afterward. When you have more than one engine, that means you still
have at least one remaining after a failure, and that means you have
decisions to make. The judgement associated with these decisions is what is
important, not merely the procedures. Trying to "...limp home on one
engine..." is a fool's errand, with many gravestones to mark the path.

John Gaquin writes:

And the above, my friend, shows precisely why separate training and
certification are required. Any airplane, from Cessna to Boeing, is fairly
easy to fly when everything goes right. Teaching the procedures involved in
an engine failure is fairly straightforward; and, like most straightforward
procedures, they are not difficult to learn with practice. But the rub
comes afterward. When you have more than one engine, that means you still
have at least one remaining after a failure, and that means you have
decisions to make. The judgement associated with these decisions is what is
important, not merely the procedures. Trying to "...limp home on one
engine..." is a fool's errand, with many gravestones to mark the path.

Well, it worked for British Airways.

I don't mean actually completing the trip as planned. I just mean
getting safely to an airport, which at least seems to be possible with
multiple engines (even on takeoff), whereas it looks pretty grim with
just one engine on the aircraft.

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Mxsmanic schrieb:

important, not merely the procedures. Trying to "...limp home on one
engine..." is a fool's errand, with many gravestones to mark the path.

Well, it worked for British Airways.

IIRC, they "limped" home on *three* engines. Slightly different and
perfectly legal.

Stefan

Mxsmanic wrote:

important, not merely the procedures. Trying to "...limp home on one
engine..." is a fool's errand, with many gravestones to mark the path.

Well, it worked for British Airways.

they were not flying the kind of light twins we were talking
about... different performances.

--Sylvain

Mxsmanic wrote:
Michelle P writes:


Complexity. Flight dynamics are different and the systems are more complex.
You can get a AMEL first. But why?


Mainly for the purpose of flying the same multiengine plane I fly in
simulation (a Baron 58). Of course, this aircraft costs almost two
million dollars, but if I can fantasize about having enough money for
a license, I can just as easily fantasize about having enough money to
buy a decent aircraft.

Anyway, I dislike P-factor and torque issues, and I figure they'd be
less prominent on a multiengine aircraft (especially with
counterrotating powerplants, but apparently there aren't many aircraft
like that). And I could limp home on one engine, whereas I'd be out
of luck in a single-engine plane. Given how frequently piston engines
fail, that seems like an important consideration.

Usually an engine will give you a sign before it dies. A new vibration,
a new leak....

THere are some counter rotating but they are few. The seminole is one.
It is commonly said the remaining engine on a multi engine aircraft will
carry you to the scene of the crash. YOu loose half of your power and
80% of your perfomance. Check the single engine service cielings. most
non-turbochaged are around 5000 MSL. No good if you are flying out west.
The airplane i fly has a ingle engine service cieling above 18,000. this
is useful.

Michelle P

Michelle P writes:

Usually an engine will give you a sign before it dies. A new vibration,
a new leak....

Great! That gives you time to scribble out your last will and
testament before that last spiral into terrain.

THere are some counter rotating but they are few. The seminole is one.
It is commonly said the remaining engine on a multi engine aircraft will
carry you to the scene of the crash. YOu loose half of your power and
80% of your perfomance.

So I've heard. But you're in trouble either way if there's no handy
place to land nearby. And if there _are_ handy places to land,
presumably 20% performance will get you to more of them than 0%
performance.

Check the single engine service cielings. most
non-turbochaged are around 5000 MSL. No good if you are flying out west.
The airplane i fly has a ingle engine service cieling above 18,000. this
is useful.

If the engine fails at altitude, don't you still have a fair amount of
time to fly around while it drifts down to the service ceiling for a
single engine?

Which reminds me: Does flying on one engine put hazardous stress on
the airframe? I especially wonder about twin jets, with their engines
on plyons--the eccentric stresses on the pylon and engine mount must
be tremendous with one engine doing all the work.

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Mxsmanic wrote:
[snip]


If the engine fails at altitude, don't you still have a fair amount of
time to fly around while it drifts down to the service ceiling for a
single engine?

The second engine buys you time.

Which reminds me: Does flying on one engine put hazardous stress on
the airframe? I especially wonder about twin jets, with their engines
on plyons--the eccentric stresses on the pylon and engine mount must
be tremendous with one engine doing all the work.

Not not really. unless you try acro while single engine. The pylons and
such are designed to take the stress for a certified period of time.

Michelle P