Why are multiple engines different?

Neil Gould writes:

By the time one is rated to fly -- anything, not just multi's -- one has
received training in all aspects of the operation of the plane, including
engine out. Taxiing with a single engine would be part of that training.

So why doesn't anyone seem to have done it?

--
Transpose mxsmanic and gmail to reach me by e-mail.

On Wed, 18 Oct 2006 19:07:51 +0200, Mxsmanic
wrote:

Neil Gould writes:

By the time one is rated to fly -- anything, not just multi's -- one has
received training in all aspects of the operation of the plane, including
engine out. Taxiing with a single engine would be part of that training.

So why doesn't anyone seem to have done it?

In fact, they do. I often see multis taxiing in to the ramp with just
one engine running. Mostly turboprops.

Curious coincidence: I just saw the show on CNBC about American
Airlines that they're saving a lot of fuel by taxiing on just one
engine.

RK Henry

It has to do with the thrust vector and the landing gear
geometry. Light twins tend to bind on the asymmetric thrust
and the short coupled landing gear. Turbo props and jets
are generally longer and the engines thrust further from the
nose wheel. On jet aircraft, the engines may be on the tail
and they can taxi just fine on one engine.

The airlines do anything to save fuel, but they do not
take-off with paying passengers aboard to save fuel. They
do start and taxi on one engine, but will start all engines
when nearing the take-off runway so the temperatures has
stabilized and the engine can be verified as running. On
airplanes with 4 engines I do understand that some flights
may be allowed to depart on three engines, but I have no
researched the FAR 25 or 121 to see. Also the particular
OPS manual for an airline would have to allow it.


--
James H. Macklin
ATP,CFI,A&P

--
The people think the Constitution protects their rights;
But government sees it as an obstacle to be overcome.
some support
http://www.usdoj.gov/olc/secondamendment2.htm
See http://www.fija.org/ more about your rights and duties.


"RK Henry" wrote in message
...
| On Wed, 18 Oct 2006 19:07:51 +0200, Mxsmanic

| wrote:
|
| Neil Gould writes:
|
| By the time one is rated to fly -- anything, not just
multi's -- one has
| received training in all aspects of the operation of
the plane, including
| engine out. Taxiing with a single engine would be part
of that training.
|
| So why doesn't anyone seem to have done it?
|
| In fact, they do. I often see multis taxiing in to the
ramp with just
| one engine running. Mostly turboprops.
|
| Curious coincidence: I just saw the show on CNBC about
American
| Airlines that they're saving a lot of fuel by taxiing on
just one
| engine.
|
| RK Henry

"Jim Macklin" wrote in message
news:OOEZg.12886$XX2.1052@dukeread04...
It has to do with the thrust vector and the landing gear
geometry. Light twins tend to bind on the asymmetric thrust
and the short coupled landing gear. Turbo props and jets
are generally longer and the engines thrust further from the
nose wheel. On jet aircraft, the engines may be on the tail
and they can taxi just fine on one engine.

Thank you Jim, I was going to bring this up but didn't think it was worth
the effort for this thread : ( I used to taxi a Lear 35 all the time on
one engine, starting the second after the batteries had a chance to
re-charge. I have also taxiied a Baron on one engine but it was always on a
hardsurface without any uphill incline. The distance between the thrust
source and the steering source is the key.



The airlines do anything to save fuel, but they do not
take-off with paying passengers aboard to save fuel. They
do start and taxi on one engine, but will start all engines
when nearing the take-off runway so the temperatures has
stabilized and the engine can be verified as running. On
airplanes with 4 engines I do understand that some flights
may be allowed to depart on three engines, but I have no
researched the FAR 25 or 121 to see. Also the particular
OPS manual for an airline would have to allow it.

Boeing 727 also has procedure for two-engine take-off but usually only
minimum crew to ferry it to a place it can be worked on.




--
James H. Macklin
ATP,CFI,A&P

--
The people think the Constitution protects their rights;
But government sees it as an obstacle to be overcome.
some support
http://www.usdoj.gov/olc/secondamendment2.htm
See http://www.fija.org/ more about your rights and duties.


"RK Henry" wrote in message
...
| On Wed, 18 Oct 2006 19:07:51 +0200, Mxsmanic

| wrote:
|
| Neil Gould writes:
|
| By the time one is rated to fly -- anything, not just
multi's -- one has
| received training in all aspects of the operation of
the plane, including
| engine out. Taxiing with a single engine would be part
of that training.
|
| So why doesn't anyone seem to have done it?
|
| In fact, they do. I often see multis taxiing in to the
ramp with just
| one engine running. Mostly turboprops.
|
| Curious coincidence: I just saw the show on CNBC about
American
| Airlines that they're saving a lot of fuel by taxiing on
just one
| engine.
|
| RK Henry

I think that things as simple as tire pressures and surface
would make a difference. Slope or runway gradients, current
wind would have a big effect. a crosswind might cancel the
turning moment of a single-engine or magnify it.

I've had a number of engine failures, except for one at my
home airport. After landing I would coast off the runway
and just call for a tow. When I had both fuel pumps on the
left engine of a BE 58P fail down in Texas, I just did the
same thing, landed, coasted clear and arranged for a tow to
the ramp. If I had tried to taxi and had a problem, I could
have been blocking a taxiway and caused a real problem to
the ground controller.
For those who will ask, I was returning to Wichita from
Brownsville after dropping the aircraft owners off for the
week. At FL240 near Corpus Christi the left engine died
when I turned the boost pump off [I had been using the pumps
because of hot fuel and vapor suppression on the ground]
Then the engine would not start again because of zero fuel
pressure. Did not attempt cross-feed from the right because
of concern about possible broken fuel lines.
The most difficult decision was selecting a place to land,
it does take a while to come down from FL240 and I wanted a
place where I could get repairs and an airline flight out.
It was Mothers' Day week-end so I knew there would be no
work done for a while and my wife probably wanted me home.
Declared an emergency just because I wanted the priority
handling and no traffic I had to follow. The shop in San
Antoine repaired the pumps and I picked it up the next week.
Later, back at home we ended up replacing all the pumps with
new pumps. There was still too much fuel pressure
variation. The airplane was an early 58P and it had many
hours in service formerly in air taxi service in Europe.


"Allen" wrote in message
om...
|
| "Jim Macklin" wrote
in message
| news:OOEZg.12886$XX2.1052@dukeread04...
| It has to do with the thrust vector and the landing gear
| geometry. Light twins tend to bind on the asymmetric
thrust
| and the short coupled landing gear. Turbo props and
jets
| are generally longer and the engines thrust further from
the
| nose wheel. On jet aircraft, the engines may be on the
tail
| and they can taxi just fine on one engine.
|
| Thank you Jim, I was going to bring this up but didn't
think it was worth
| the effort for this thread : ( I used to taxi a Lear 35
all the time on
| one engine, starting the second after the batteries had a
chance to
| re-charge. I have also taxiied a Baron on one engine but
it was always on a
| hardsurface without any uphill incline. The distance
between the thrust
| source and the steering source is the key.
|
|
|
| The airlines do anything to save fuel, but they do not
| take-off with paying passengers aboard to save fuel.
They
| do start and taxi on one engine, but will start all
engines
| when nearing the take-off runway so the temperatures
has
| stabilized and the engine can be verified as running.
On
| airplanes with 4 engines I do understand that some
flights
| may be allowed to depart on three engines, but I have no
| researched the FAR 25 or 121 to see. Also the
particular
| OPS manual for an airline would have to allow it.
|
| Boeing 727 also has procedure for two-engine take-off but
usually only
| minimum crew to ferry it to a place it can be worked on.
|
|
|
|
| --
| James H. Macklin
| ATP,CFI,A&P
|
| --
| The people think the Constitution protects their rights;
| But government sees it as an obstacle to be overcome.
| some support
| http://www.usdoj.gov/olc/secondamendment2.htm
| See http://www.fija.org/ more about your rights and
duties.
|
|
| "RK Henry" wrote in message
| ...
| | On Wed, 18 Oct 2006 19:07:51 +0200, Mxsmanic
|
| | wrote:
| |
| | Neil Gould writes:
| |
| | By the time one is rated to fly -- anything, not
just
| multi's -- one has
| | received training in all aspects of the operation
of
| the plane, including
| | engine out. Taxiing with a single engine would be
part
| of that training.
| |
| | So why doesn't anyone seem to have done it?
| |
| | In fact, they do. I often see multis taxiing in to the
| ramp with just
| | one engine running. Mostly turboprops.
| |
| | Curious coincidence: I just saw the show on CNBC about
| American
| | Airlines that they're saving a lot of fuel by taxiing
on
| just one
| | engine.
| |
| | RK Henry
|
|
|
|

"Allen" wrote

Boeing 727 also has procedure for two-engine take-off

???

What, like a normal operations?
--
Jim in NC

"Morgans" wrote in message
...

"Allen" wrote

Boeing 727 also has procedure for two-engine take-off

???

What, like a normal operations? --
Jim in NC

Umm, how many engines does a Boeing 727 have? I don't understand your
question. It would not be normal to T.O. with one of the three engines
inop.

allen

On Thu, 19 Oct 2006 21:57:43 GMT, "Allen"
wrote:


"Morgans" wrote in message
...

"Allen" wrote

Boeing 727 also has procedure for two-engine take-off

???

What, like a normal operations? --
Jim in NC

Umm, how many engines does a Boeing 727 have? I don't understand your
question. It would not be normal to T.O. with one of the three engines
inop.

allen

http://en.wikipedia.org/wiki/United_Airlines_Flight_266

Don

"Allen" wrote in message
om...

"Morgans" wrote in message
...

"Allen" wrote

Boeing 727 also has procedure for two-engine take-off

???

What, like a normal operations? --
Jim in NC

Umm, how many engines does a Boeing 727 have? I don't understand your
question. It would not be normal to T.O. with one of the three engines inop.

Ooops! I was thinking of a 717, I think.
--
Jim in NC

On Thu, 19 Oct 2006 05:12:46 GMT, RK Henry
wrote:

On Wed, 18 Oct 2006 19:07:51 +0200, Mxsmanic
wrote:

Neil Gould writes:

By the time one is rated to fly -- anything, not just multi's -- one has
received training in all aspects of the operation of the plane, including
engine out. Taxiing with a single engine would be part of that training.

So why doesn't anyone seem to have done it?

In fact, they do. I often see multis taxiing in to the ramp with just
one engine running. Mostly turboprops.

That saves more than fuel. Time to overhaul on those engines is
measured in both total hours and number of starts. When you are
looking at several hundred thousand dollars for a small one and who
knows for the large ones it behooves them to keep the number of starts
down.



Curious coincidence: I just saw the show on CNBC about American
Airlines that they're saving a lot of fuel by taxiing on just one
engine.



RK Henry
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com