Why are multiple engines different?

"Mxsmanic" wrote in message

.....I wouldn't want to have to
deal with that in real life. Still, I'd have a better chance than I
would with an engine failure in a single-engine plane.

Surprisingly, I don't think the record bears that out, or at least not
nearly so much as you might think. As I posted earlier, it is the decision
making that tends to bite people concerning a failure in a twin. In a
single, the biggest, most crucial decision is made for you as soon as the
engine fails.

John Gaquin writes:

Surprisingly, I don't think the record bears that out, or at least not
nearly so much as you might think. As I posted earlier, it is the decision
making that tends to bite people concerning a failure in a twin. In a
single, the biggest, most crucial decision is made for you as soon as the
engine fails.

But with a single, your only option is to find a place to land,
quickly. If you have two engines with one running, you should have an
indefinite period of flight left during which you can look for a more
suitable landing spot (the assumption still being that you will land
ASAP once the engine has failed).

I've tried single failures on take-off in a twin in the sim; it's
difficult to wrestle the aircraft into level flight, but I was able to
land at a nearby airport (Boeing field after leaving KSEA, if you must
know), although I died the first two or three times I tried it. I
haven't bothered to try it in a single, since I figure I'd be doomed
in any case.

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"Mxsmanic" wrote in message

But with a single, your only option is to find a place to land,
quickly. If you have two engines with one running, you should have an
indefinite period of flight left during which you can look for a more
suitable landing spot (the assumption still being that you will land
ASAP once the engine has failed).

Precisely my point, (except for the "...indefinite period..." part). If an
engine fails in a single, you are going to land, now. After a failure in a
twin, you have choices, but without proper training and mindset, most light
twin pilots don't seem to have a realization of just how marginal and
limited those choices become. Most light twins do not fly well on one
engine.


........ although I died the first two or three times I tried it. I
haven't bothered to try it in a single, since I figure I'd be doomed
in any case.

A faulty assumption. I believe that engine failure in light twins leads to
more accidents/injuries than in singles. A light twin is squirrelly on one
engine, and apparently gives some pilots a false sense of security.

John Gaquin writes:

Precisely my point, (except for the "...indefinite period..." part). If an
engine fails in a single, you are going to land, now. After a failure in a
twin, you have choices, but without proper training and mindset, most light
twin pilots don't seem to have a realization of just how marginal and
limited those choices become. Most light twins do not fly well on one
engine.

I'd interpret any engine failure as a sign from above to land
immediately. I figure a twin might just let you reach a bit further
in search of an airfield, nothing more.

Now if you have three or more engines, perhaps the situation is
different. I once read that Boeing would demonstrate its 727 to
prospective buyers by taking off and setting one engine to idle as the
aircraft left the runway. The aircraft never even skipped a beat,
apparently.

A faulty assumption. I believe that engine failure in light twins leads to
more accidents/injuries than in singles. A light twin is squirrelly on one
engine, and apparently gives some pilots a false sense of security.

But if you don't have the false sense of security, you're still better
off, right?

I guess one can do the numbers. If the change of an engine failure is
one in 1000, then the chance of losing all power in a single is one in
1000, and the chance of losing all power in a twin is one in
1,000,000. The chance of losing 80% power is slightly less than one
in 500 in a twin, though (because the more engines you have, the more
likely you are to lose at least one).

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"Mxsmanic" wrote in message

Now if you have three or more engines, perhaps the situation is
different. I once read that Boeing would demonstrate its 727 to
prospective buyers by taking off and setting one engine to idle as the
aircraft left the runway. The aircraft never even skipped a beat,
apparently.

Having flown a 727 for some time, I wouldn't quite say it never skipped a
beat, but it is a marvelous airplane that (in most models) does quite well
on two engines. But more to your point, in the above paragraph, you are
referencing a transport category aircraft, in which it is standard procedure
to continue the takeoff with an engine failure after V1 -- indeed, it is a
matter of regulation. This does not apply in the Baron to which you
referred.


But if you don't have the false sense of security, you're still better
off, right?

No. That's the point.


I guess one can do the numbers. If the change of an engine failure is
one in 1000, then the chance of losing all power in a single is one in
1000, and the chance of losing all power in a twin is one in
1,000,000. The chance of losing 80% power is slightly less than one
in 500 in a twin, though (because the more engines you have, the more
likely you are to lose at least one).

You know, Mx, now you're becoming argumentative (again). You can play all
you want at manipulating made-up numbers. You come here and ask for
information and advice, then argue over the validity of the response. You
would do well to remember this small point: You do not know what you're
talking about. We do.

John Gaquin writes:

You know, Mx, now you're becoming argumentative (again). You can play all
you want at manipulating made-up numbers.

I'm not making things up. If engine reliability is constant, the
chances of a failure in a twin are higher than they are in a single.
This must be balanced against the airworthiness of the twin with one
engine inoperative in order to determine which type of aircraft is
better (which in turn obviously requires comparing specific aircraft).

Irrespective of aircraft, if the engines are constant, then the chance
of an engine failure is always higher in the twin, but the chance of a
total loss of engine power in the twin is lower.

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Recently, Mxsmanic posted:

John Gaquin writes:

You know, Mx, now you're becoming argumentative (again). You can
play all you want at manipulating made-up numbers.

I'm not making things up.

Yes, you are.

If engine reliability is constant, the
chances of a failure in a twin are higher than they are in a single.

The trouble is, this is not relevant to the likelihood of survival. There
are other factors.

Irrespective of aircraft, if the engines are constant, then the chance
of an engine failure is always higher in the twin, but the chance of a
total loss of engine power in the twin is lower.

And, as is often said, "...the second engine will fly you to the scene of
the crash". Once again: the chances of survival are not directly
correlated with the loss of total power in a light twin.

You have received several polite and factual responses from pilots who
understand these factors. I don't understand why you continue to argue the
facts, given your status. Please, argue your position in some sim group,
where all things are "equal".

Neil

Mxsmanic wrote in
:

I'm not making things up. If engine reliability is constant, the
chances of a failure in a twin are higher than they are in a single.

If you are not making things up, back up your statements with references.
Until you do so, you have no credibility.

Allen

Mxsmanic wrote in
:

John Gaquin writes:

You know, Mx, now you're becoming argumentative (again). You can
play all you want at manipulating made-up numbers.

I'm not making things up.

You seem to be.

If engine reliability is constant, the
chances of a failure in a twin are higher than they are in a single.

Different engines have different failure probabilities.

In addition, the addition rule for probabilities is

P(A or B) = P(A) + P(B) - P(A and B)

You simply cannot assume that either one engine fails or the other and
not both at the same time.

Second, you cannot assume that the probability of a failure of an egine
on a single engine plane is the same as the probability of failure of a
different engine installed in different aircraft.

These probabilities come from engineering, testing, operation modes,
observed frequencies of failures etc. Proper maintenance or lack thereof
can also affect the probabilities. Thus, the antecedent of the statement
you make below

... if the engines are constant, then the chance
of an engine failure is always higher in the twin, but the chance of a
total loss of engine power in the twin is lower.


is false. Now you can go ahead and prove that 2 + 2 = 5.


Sinan

--
A. Sinan Unur
(remove .invalid and reverse each component for email address)

Mxsmanic wrote in
:

John Gaquin writes:

Surprisingly, I don't think the record bears that out, or at least
not nearly so much as you might think. As I posted earlier, it is
the decision making that tends to bite people concerning a failure in
a twin. In a single, the biggest, most crucial decision is made
for you as soon as the engine fails.

But with a single, your only option is to find a place to land,
quickly. If you have two engines with one running, you should have an
indefinite period of flight left during which you can look for a more
suitable landing spot (the assumption still being that you will land
ASAP once the engine has failed).


This is not necessarily true. A light twin such as the one I trained in
(piper seneca) at 4000 pounds the absolute ceiling is 20,000 msl. With
one engine out, the absolute ceiling becomes only 6,600. That is on a
standard day. If you understand density altitude then consider
mountainous terrain on a HOT day. I trained in Phoenix and on a hot day
with one engine shut down I would sometimes still be loosing 100 feet
per minuet at 5,000 feet MSL. That put me 3,500 feet above the ground
and still loosing altitude.

Then there's loosing an engine on climb out after takeoff. My charts
say at sea lv on standard day (15C, and 29.92) and max weight, you will
get about 180 FPM climb. At 4000 ft a zero climb rate. If there are
obstacles you may not clear them. This is part of your preflight
planning in a multi-engine airplane.

My instructor always said the working engine only helps you get to the
crash sight. I'm not sure I like that, but it stresses getting the
plane down at the nearest safe place and all the importance of the
decision making that goes along with it.