babumushai
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Questions About Operations With Engines Turned Off

Fri Jun 24, 2005 9:45 am

1.Can a aircraft be pushed back and taken from parking bay to runway with out starting on the engine's with full load on board with push back engine?
2.If its done so will it cause and problems to the passengers on board or the cargo on board?
3.Can a aircraft switch of its one engine out of two engine's (b737,a320 or atr's) and glide down and make its landings?
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mNeo
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Questions About Operations With Engines Turned Off

Fri Jun 24, 2005 9:56 am

Not a pilot but might help you there

1. Yes, there were neumerous stories about how the UA747(i think) was towed to the runway beacuase the fuel burn from taxing would be to much inorder to fly the route (ORD-HKG i beilve)

2. I wount belive so, beacause the APU must run inorder to provide bleed air and electircity, this would power the Air conditioning and other systems that woud be nessesary for passengers and cargo

3: no idea
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rendezvous
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Questions About Operations With Engines Turned Off

Fri Jun 24, 2005 10:14 am

Well aircraft can make landings with an engine inop, but shutting down an engine in flight uncessarily compromises safety.
 
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VirginFlyer
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RE: Questions About Operations With Engines Off

Fri Jun 24, 2005 10:37 am

An aircraft would be able to land without an engine switched off, however it would a) be illegal, and more importantly b) be very unsafe. Think about it this way. You're on final, about to land, and another aircraft enters the runway without clearance. When this happens, you have to go-around. Now, if you have one engine shut down, you are going to have a lot of trouble doing this.

A twin should be able to climb out with one engine inoperative, but you wouldn't want to be doing it by choice - your climb gradient isn't going to be flash and you are going to have to throw in a lot of rudder to counter the yaw from the assymetric thrust. If you are below a certain speed (Blue Line it is referred to in light twins, I guess it would be the same in a larger aircraft), the aircraft may not be controllable at all.

Even worse, if you were to lose the engine which was running for some reason, then you would be in quite a predicament, especially if you needed to go around. Jet engines can't just be switched on and develop full power instantly - they take time to spool up.

(Unrelated to the question, but the lag in engine response is also a reason why they run the engines up partially just before going to full power on a take off - because of the lag in response, it may not become evident that an engine isn't producing power until the other engines are all at full throttle, and by then it will take a while to bring them back down. Again, not a nice situation to be in. Aircraft have been lost because of this in the past.)

Back to the question, once they are on the ground (and I would expect clear of the runway), it is a different story. I am aware of at least one airline which taxis ATR 72s back to the terminal on a single engine. But you should never see it being done in the air. It is simply too reckless.

V/F
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B744F
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RE: Questions About Operations With Engines Turned Off

Fri Jun 24, 2005 10:46 am

Emb-120s also taxi on one engine, to save fuel.
 
Ralgha
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RE: Questions About Operations With Engines Turned Off

Fri Jun 24, 2005 12:12 pm

Quoting B744F (Reply 4):
Emb-120s also taxi on one engine, to save fuel.

No they don't. I fly them, we run both engines.

Any airplane that taxis on one engine is COMPANY policy, not airplane specific.
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HAWK21M
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RE: Questions About Operations With Engines Turned Off

Fri Jun 24, 2005 2:31 pm

1.Can a aircraft be pushed back and taken from parking bay to runway with out starting on the engine's with full load on board with push back engine
It can.But not done out here.By Starting up on the Bay or After Pushback the Parameters are checked for Satisfactory performance,prior to Roll out.It would be unnecessary to have to be towed back in case of a Startup problem.Also Out here During Grd start.Mx personnel are present on the Tarmec,but Forbidden on Runway,unless its required for Emergency Towing ops or Snag.
Not Advisable having Persons around an Active Runway.

2.If its done so will it cause and problems to the passengers on board or the cargo on board
No Problems to the Pax or Cargo,as APU will be functioning to provide Air Conditioning & Lighting.

3.Can a aircraft switch of its one engine out of two engine's (b737,a320 or atr's) and glide down and make its landings.
Its Possible.But will never be done unless an Emergent situation exists due Snag.As mentioned above.In case of a Go-Around it would be a problem.

regds
MEL
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Santhosh
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RE: Questions About Operations With Engines Turned Off

Fri Jun 24, 2005 3:13 pm

Are there different categories/classification of push back trucks of different capacities and capabilities? Or Are they more standardized piece of machinery? And how much load can take generally while pushing back heavy aircrafts?

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George
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HAWK21M
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RE: Questions About Operations With Engines Turned Off

Fri Jun 24, 2005 4:15 pm

Tow Tractors
Tow Tractors

Out here at Bom.AI,IC,9W,Cambata & AAI have their own Push backs or Tow Tractors.

regds
MEL

[Edited 2005-06-24 09:17:11]
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northseatiger
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RE: Questions About Operations With Engines Turned Off

Fri Jun 24, 2005 5:46 pm

The EH101 takes off on 3 engines and routinley shuts one down in flight whilst carrying out missions
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Santhosh
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RE: Questions About Operations With Engines Turned Off

Fri Jun 24, 2005 6:29 pm

MEL-Thanx for the links yar.That gives a better idea.

Regards
George
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yul332LX
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RE: Questions About Operations With Engines Turned Off

Sat Jun 25, 2005 9:21 am

On some aircraft type, AA's been using only one engine to taxi, whenever possible, for the last 6 or 7 months.

AA has estimated that the annual saving is around $2,5 million.
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HAWK21M
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RE: Questions About Operations With Engines Turned Off

Sat Jun 25, 2005 12:13 pm

Quoting YUL332LX (Reply 11):
On some aircraft type, AA's been using only one engine to taxi, whenever possible, for the last 6 or 7 months.

AA has estimated that the annual saving is around $2,5 million

This One Engine Taxi is Prior to T/O or After Landing.The Latter makes Business sense.
regds
MEL
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XFSUgimpLB41X
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RE: Questions About Operations With Engines Turned Off

Sat Jun 25, 2005 12:57 pm

Here's some non-error filled information like what has been posted above:


"1.Can a aircraft be pushed back and taken from parking bay to runway with out starting on the engine's with full load on board with push back engine?"


Sure.... that would not be a problem. It would save fuel. I make it standard practice to only start one engine out of the gate and crank the number 1 engine as we get closer to the runway. The more fuel I have in the tanks at takeoff the happier that I am.





2.If its done so will it cause and problems to the passengers on board or the cargo on board?




Most certainly not- The APU has plenty of electrical power to power the whole aircraft and the air conditioning is very strong.





3.Can a aircraft switch of its one engine out of two engine's (b737,a320 or atr's) and glide down and make its landings?





Not only can we descend down and land without much problem on only one engine, but we can actually have an engine fail on the takeoff roll, CONTINUE the takeoff and climb out with obstacle clearance guarantee. We can mope around on one engine all day long... there is a tremendous amount of power that comes out of those things. If there is a need for a go around on one engine..its really not that big of an issue.
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DC8FriendShip
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RE: Questions About Operations With Engines Turned Off

Sun Jun 26, 2005 2:27 am

Quoting Santhosh (Reply 7):
Are there different categories/classification of push back trucks of different capacities and capabilities?

Many more than I can list- varying from a small lektro to a towbarless tractor capable of moving the A380. We have two here- a S&S GT35 good for narrowbodies and RJ's, and a 60's model Hough paymover, good for narrow and wide bodies up to 747- 300.
The Hough
http://www.victorygse.com/images/pho...os/pushback/pushback2--T300(1).jpg
I couldn't find a pic of a S&S
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HAWK21M
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RE: Questions About Operations With Engines Turned Off

Sun Jun 26, 2005 6:23 pm

Quoting MNeo (Reply 1):
1. Yes, there were neumerous stories about how the UA747(i think) was towed to the runway beacuase the fuel burn from taxing would be to much inorder to fly the route (ORD-HKG i beilve)

Any other Examples of Aircraft being towed to the "Runway" prior to Startup.
regds
MEL
I may not win often, but I damn well never lose!!! ;)

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