swank300
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Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 3:43 pm

Hey Fellow A.neters, have a question for you.

I'm a big fan of the B777 and B767 and I also often fly the B757. I know Airbus has publicly said it is safer to have four engines as opposed to two, especially overwater. I have heard that the 747 can fly on one engine if need be. But, I was wondering, in your opinions, if these two-engine planes can properly fly if one of these engines failes and also if a captain would immediately declare an emergency and immediately land or if it is normal enough that they would fly to a preferable airport and dump fuel....basically, how severe is losing an engine on a two-engine plane? Thanks in advance....
 
QXatFAT
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 3:46 pm

Nice post. I cant wait to get a.netters answers as I do not know if they can haha  Smile Thanks for posting this Swank300.
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777STL
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 3:47 pm

Quoting Swank300 (Thread starter):
Hey Fellow A.neters, have a question for you.

I'm a big fan of the B777 and B767 and I also often fly the B757. I know Airbus has publicly said it is safer to have four engines as opposed to two, especially overwater. I have heard that the 747 can fly on one engine if need be. But, I was wondering, in your opinions, if these two-engine planes can properly fly if one of these engines failes and also if a captain would immediately declare an emergency and immediately land or if it is normal enough that they would fly to a preferable airport and dump fuel....basically, how severe is losing an engine on a two-engine plane? Thanks in advance....

No they drop out of the sky, happens quite often, surprised you haven't heard about it.
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atmx2000
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 3:48 pm

Yes. Read about ETOPS.
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DLKAPA
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 4:02 pm

Quoting 777STL (Reply 2):

No they drop out of the sky, happens quite often, surprised you haven't heard about it.

So that explains the big coke can that landed in my backyard yesterday!
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antskip
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 4:03 pm

Quoting Swank300 (Thread starter):
how severe is losing an engine on a two-engine plane?

The above quote is more what you are asking than your choice of topic:

Quoting Swank300 (Thread starter):
Can A 777/767/757 Fly Only On One Engine?

To me one way at looking at safety question is not: "how many engines do you have?", but rather, once an engine does fail, how many have you left before you become a glider? Once a two-engine plane has engine failure you are one engine failure away from going down.
 
superhub
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 4:05 pm

I believe Boeing did some testing with a B757 in Urumqi (whose airport is some thousands feet elevated). The B757 took off with one engine and flew around with only one engine before returning safely. Not sure about whether they did it with a full load though. But I am pretty sure the B757 engines are pretty powerful.
 
CRJ705
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 4:30 pm

I believe that a twin engine commercial aircraft will have to make a diversion if the engine is down to the nearest airport, but it will still fly and most, if not all, of the avionics and all the critical systems will work. This is governed under Extended Twin Engine OPerationS (ETOPS) and is applicable to planes that cross into areas uninhabitable by people, and twin engine aircraft may only fly a maximum of 180 minutes from a diversionary airport when flying over oceans or land masses that do not have airports. This is a precautionary measure because if an engine fails, there is only one left and therefore it is better to error on the side of caution. As such twin engine aircraft, at least for the time being, is not suitable for some routes where a plane is over water for over three hours. I hope this answers your question.

Regards
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ManuCH
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 4:36 pm

Statistically it's more likely to experience an engine failure in a 4-engine aircraft than in a twin, thus possibly causing more diversions (it's simple math). But it's also more likely to loose *both* engines in a twin than all 4 in a 4-engine plane...

Other question: how many engines does an A340-B747 need to still be able to operate safely? And does this statistical difference (4 vs 2 engines) really make a difference in real-world operations, ie. do quads have more emergency landings because of engine failures (in %) when compared to twins?
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Shenzhen
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 4:47 pm

I think they can all fly with no engines...... just not very long.

Cheers
 
MD-90
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 5:19 pm

Quoting Swank300 (Thread starter):
I have heard that the 747 can fly on one engine if need be.

That one engine will be taking you to the airport, immediately, or to the scene of the crash. A light 747 can stay aloft with only two engines, but not a heavy one. The one engine is needed to power the hydraulics.

Quoting ManuCH (Reply 8):
But it's also more likely to loose *both* engines in a twin than all 4 in a 4-engine plane...

I don't think it's more likely to have a complete failure on a twin versus a quad. The only kinds of failures that would render all engines inop are likely to be system failures of such magnitude that they affect all engines, no matter how many you have (such as running out of fuel).
 
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solnabo
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 5:46 pm

Well, there was Air Transat A330 glided to the Azores, dont know how many miles thou w/ no engines running (fuel leak). No crash exept blown tires..

Good work

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murchmo
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 6:05 pm

yes they can fly with just one. part of multi-engine training is practicing an engine failure. You must be able to handle a plane with a catostrophic engine failure, fly it and land it on one engine....pretty sure that applies for a 777/767/757 type-rating...
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Oryx
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 6:20 pm

Quoting Swank300 (Thread starter):
I know Airbus has publicly said it is safer to have four engines as opposed to two, especially overwater.

Thats wy they build only two engine planes for the first 20(?) yearsof theire existence. They never said that it is saver - they only said that less restrictions upply if you have more spare engines. Restrictions are: routing over remote areas and MTOW whith an imposed climb gradient due to terrain avoidence etc.
 
gearup380
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 7:31 pm

Quoting Solnabo (Reply 11):
Well, there was Air Transat A330 glided to the Azores, dont know how many miles thou w/ no engines running (fuel leak). No crash exept blown tires..

Wow, any records / images / videos of this one?
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andz
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 7:43 pm

Quoting Gearup380 (Reply 14):
Wow, any records / images / videos of this one?

Watch Discovery or National Geographic channel, it comes up time and again.
After Monday and Tuesday even the calendar says WTF...
 
antiuser
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 7:50 pm

Quoting Swank300 (Thread starter):
I know Airbus has publicly said it is safer to have four engines as opposed to two, especially overwater.

The whole "4 engines 4 long haul" thing was started by Sir Richard Branson and not Airbus...
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TGV
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 10:40 pm

Avoid 777 with 3-4-3 config in Y ! They are real sardine cans
 
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 10:47 pm

Quoting 777STL (Reply 2):
No they drop out of the sky, happens quite often, surprised you haven't heard about it.

We have a new member who may not know as much about airplanes as you do. The person posted a question and some how you decided to tear into them. Does that make you feel powerful and superior to tear into someone who does not know.

Peopls complain abot low quality posts in here. Please explain to me what makes the above referanced quote a high quality one?

When someone new shows up and askes a valid question why not share your knowledge with them and help them learn before you tear into them.

To the thread starter. Ignore the idiots you will learn who the quality people are soon enough.


Go http://en.wikipedia.org/wiki/ETOPS here if you would like to learn about etops in an easy to understand fashion.

GS
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viv
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 10:48 pm

Yes, all twin engined airliners are certified to fly on one engine.

Reminds me of the story of the F-16 pilot who asked for a priority approach because his engine was running a little hot. He was told to slot in behind a B-52 which was landing with one engine shut down.

"Ah", replied the F-16 pilot. "The dreaded 7-engine approach"!
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TinkerBelle
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 10:53 pm

Quoting Swank300 (Thread starter):
I have heard that the 747 can fly on one engine if need be.

Not true.

Quoting Antiuser (Reply 16):
The whole "4 engines 4 long haul" thing was started by Sir Richard Branson and not Airbus...

Airbus later adopted the quote.

You should probably google ETOPS..... or even check out the A.net search under ETOPS.

Quoting 777STL (Reply 2):
No they drop out of the sky, happens quite often, surprised you haven't heard about it.

Nice reply  biggrin 
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Starlionblue
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 10:57 pm

Quoting Antskip (Reply 5):

To me one way at looking at safety question is not: "how many engines do you have?", but rather, once an engine does fail, how many have you left before you become a glider? Once a two-engine plane has engine failure you are one engine failure away from going down.

You are correct, but "one engine away from going down" is actually quite a long way. That is, engines fail extremely seldom. The likelyhood of two unrelated failures on the same flight is astronomical. You're more likely to be hit by a meteor while walking down the street. If two engines fail for the same reason, that sort of thing is just as likely to bring down a quad.

Quoting ManuCH (Reply 8):
Statistically it's more likely to experience an engine failure in a 4-engine aircraft than in a twin, thus possibly causing more diversions (it's simple math). But it's also more likely to loose *both* engines in a twin than all 4 in a 4-engine plane...

Other question: how many engines does an A340-B747 need to still be able to operate safely? And does this statistical difference (4 vs 2 engines) really make a difference in real-world operations, ie. do quads have more emergency landings because of engine failures (in %) when compared to twins?

You are correct that a failure in a quad is more likely. However a quad may in most cases continue on three while a twin needs to land ASAP on one. So no, you don't have more emergency landings.

Quoting Solnabo (Reply 11):
Well, there was Air Transat A330 glided to the Azores, dont know how many miles thou w/ no engines running (fuel leak). No crash exept blown tires..

That was not really an engine failure but a fuel system problem. If the plane had been a quad it would have have had exactly the same problem.



To answer the original poster, all commercial aircraft (with a few exceptions for singles) must be able to continue take-off after an engine failure and also climb out. On a twin, this means doing it on one. On a quad, this means doing it on three. If you do the math, this means that twins need to be about 50% more powerful than quads, all other things being equal.

ETOPS regulations may be used by certain twins to fly more than a certain number of minutes from the nearest suitable airfield.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
fr8mech
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 11:15 pm

All air transport rated twins can not only fly on one engine, but can continue a take-off passed V1 should engine failure occur.

Quoting ManuCH (Reply 8):
Statistically it's more likely to experience an engine failure in a 4-engine aircraft than in a twin, thus possibly causing more diversions (it's simple math). But it's also more likely to loose *both* engines in a twin than all 4 in a 4-engine plane...

Be careful with that mathematical assumption. ETOPS certified engines/airframes are maintained more rigorousley. Or make specifically, have more rigorous inspection and check-out procedures after maintenance is performed. Thus, it follows that an engine hanging on an ETOPS airframe may be better maintained and less likely to fail than the same type engine hanging on a non-ETOPS airframe.
When seconds count...the police are minutes away.
 
viv
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 11:19 pm

Quoting Fr8Mech (Reply 22):
But it's also more likely to loose *both* engines in a twin than all 4 in a 4-engine plane...

Not so. The most likely cause of losing all engines - in any aircraft - would be fuel starvation. Statistically, a fuel starvation incident is not more likely in a twin than in a quad.
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777STL
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 11:37 pm

Quoting Greasespot (Reply 18):
We have a new member who may not know as much about airplanes as you do. The person posted a question and some how you decided to tear into them. Does that make you feel powerful and superior to tear into someone who does not know.

"Tear into them"? I provided an answer! Big grin

Rest assured, if I'm "tearing into" you, you'll know it.

Anyway, grow a sense of humor....sheesh.
PHX based
 
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Starlionblue
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 11:38 pm

Quoting Viv (Reply 23):
Quoting Fr8Mech (Reply 22):
But it's also more likely to loose *both* engines in a twin than all 4 in a 4-engine plane...

Not so. The most likely cause of losing all engines - in any aircraft - would be fuel starvation. Statistically, a fuel starvation incident is not more likely in a twin than in a quad.

Exactly. The whole ETOPS concept is based on the fact that anything which makes both engines on a twin fail is just as likely to make all four engines on a quad fail.

It is of course more likely to lose both engines in a twin than all four in a quad. But the probabilities involved are so infinitesimally small that it's really nothing to worry about.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
viv
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 11:39 pm

Quoting 777STL (Reply 24):
I provided an answer!

Which was neither meaningful nor infomative.

There are no stupid questions, only stupid answers ...

[Edited 2006-03-01 15:43:33]
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777STL
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 11:46 pm

Quoting Viv (Reply 26):
There are no stupid questions, only stupid answers ...

I beg to differ. Again, some of you need to get a sense of humor, this is an internet forum, not a life or death situation.
PHX based
 
viv
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 11:48 pm

Quoting 777STL (Reply 24):
Rest assured, if I'm "tearing into" you, you'll know it.

Like being hit by a wet fish, perhaps?
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AR385
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 11:48 pm

Quoting Starlionblue (Reply 21):
That was not really an engine failure but a fuel system problem. If the plane had been a quad it would have have had exactly the same problem.

It was a faulty-maintenance induced leak made worst by the pilot's lack of training and unfortunate decisions regarding the information given by the fuel management system.
 
mdaigle
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 11:49 pm

It has been proven that the 767 can fly with no engines when an Air Canada aircraft ran out of fuel and landed in Gimli, Manitoba. This aircraft still flies to this day and is known as the Gimli Glider. Lots of information about this one, including this summary:

http://www.casa.gov.au/fsa/2003/jul/22-27.pdf

Michel
 
chris133
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 11:51 pm

I do know that twin engine planes in the US have to be able to get off the ground on one engine. That meaning, one engine must be able to get the aircraft into the air even at it's MTOW. Example: If you are at Vr and lose an engine, the remaining one must be able to get the plane off the ground safely.
 
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Starlionblue
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RE: Can A 777/767/757 Fly Only On One Engine?

Wed Mar 01, 2006 11:51 pm

Quoting Mdaigle (Reply 30):
It has been proven that the 767 can fly with no engines when an Air Canada aircraft ran out of fuel and landed in Gimli, Manitoba.

Any aircraft can fly with no engines, but most airliners can't get very far like that (unlike gliders). The typical descent gradient, is about 20:1, that is twenty feet forward for one foot of descent.

Or did you think those slender things sticking out the side of the fuse were there only to hold up the engines?  Wink
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
okelleynyc
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RE: Can A 777/767/757 Fly Only On One Engine?

Thu Mar 02, 2006 12:27 am

Quoting Starlionblue (Reply 32):
Any aircraft can fly with no engines, but most airliners can't get very far like that (unlike gliders). The typical descent gradient, is about 20:1, that is twenty feet forward for one foot of descent.

Wow, I had no idea that a typical glide ratio on a commercial airliner is around 20:1! My Ozone Mojo paraglider gets about 8:1 versus 15:1 for my hang gliding buddies. I believe a sailplane hits 60:1?

Which commercial airframe has the best average glide ratio: noting that there are a lot of variables that go into this calculation?
Just give me my Vario, my Ozone Mojo and a gorgeous day of soaring.
 
viv
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RE: Can A 777/767/757 Fly Only On One Engine?

Thu Mar 02, 2006 12:41 am

Quoting Okelleynyc (Reply 33):
I believe a sailplane hits 60:1?

Yes, a good 17 metre span sailplane can do this. I have had 5-hour flights in sailplanes, having been dropped off the tow at 2000 feet altitude.
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Starlionblue
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RE: Can A 777/767/757 Fly Only On One Engine?

Thu Mar 02, 2006 1:10 am

Quoting Okelleynyc (Reply 33):
Quoting Starlionblue (Reply 32):
Any aircraft can fly with no engines, but most airliners can't get very far like that (unlike gliders). The typical descent gradient, is about 20:1, that is twenty feet forward for one foot of descent.

Wow, I had no idea that a typical glide ratio on a commercial airliner is around 20:1! My Ozone Mojo paraglider gets about 8:1 versus 15:1 for my hang gliding buddies. I believe a sailplane hits 60:1?

Which commercial airframe has the best average glide ratio: noting that there are a lot of variables that go into this calculation?

Granted, I only have anectodal evidence of the glide ratio. But I think it stems from the fact that airliners have to fly at 30000+ feet where the air is thin. Much lift is needed to get up there, which translates into an excess of lift at lower altitudes. But it's just a theory.

More anectodal stuff: I've heard that the 737NG wants to keep flying. But I think you'll find most airliners to have good glide ratios.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
rolfen
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RE: Can A 777/767/757 Fly Only On One Engine?

Thu Mar 02, 2006 1:21 am

Yeah, unless the engine failure is paired with some catasrophic fuselage/wings damage that would modify the aerodynamic properties of the ship.
rolf
 
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Starlionblue
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RE: Can A 777/767/757 Fly Only On One Engine?

Thu Mar 02, 2006 1:36 am

Quoting Rolfen (Reply 36):
Yeah, unless the engine failure is paired with some catasrophic fuselage/wings damage that would modify the aerodynamic properties of the ship.

In the days of yore, this was sometimes a scenario. An engine fire would burn through part of the wing or a blade departure would smash through a slat section. But nowadays containment is very good.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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zeke
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RE: Can A 777/767/757 Fly Only On One Engine?

Thu Mar 02, 2006 2:22 am

Quoting Swank300 (Thread starter):
I have heard that the 747 can fly on one engine if need be.

Fly yes, maintain altitude no. The windmilling engines will supply hydraulic pressure.

Quoting Swank300 (Thread starter):
But, I was wondering, in your opinions, if these two-engine planes can properly fly if one of these engines failes and also if a captain would immediately declare an emergency and immediately land or if it is normal enough that they would fly to a preferable airport and dump fuel....basically, how severe is losing an engine on a two-engine plane?

Twin - straight failure -PAN come back to land, consider overweight. Twin/Quad fire MADAY - immidiate return. Quad - straight failure no emergency.

Quoting Superhub (Reply 6):
B757 took off with one engine and flew around with only one engine before returning safely.

Would have been a failure on the takeoff roll, not from zero speed.

Quoting ManuCH (Reply 8):
Other question: how many engines does an A340-B747 need to still be able to operate safely?

2

Quoting ManuCH (Reply 8):
And does this statistical difference (4 vs 2 engines) really make a difference in real-world operations, ie. do quads have more emergency landings because of engine failures (in %) when compared to twins?

Engines are very reliable. 2/big number or 4/big number, is close enough to 1/big number.

Quoting Starlionblue (Reply 21):
You are correct that a failure in a quad is more likely.

Whilst I would have agreed with you 10-15 years ago when the powerplants on quads were the biggest about, I see them as being more mature now.

Quoting Starlionblue (Reply 21):
To answer the original poster, all commercial aircraft (with a few exceptions for singles) must be able to continue take-off after an engine failure and also climb out. On a twin, this means doing it on one. On a quad, this means doing it on three. If you do the math, this means that twins need to be about 50% more powerful than quads, all other things being equal.

Quads are certified for a higher one engine out climb gradient.

Quoting Fr8Mech (Reply 22):
ETOPS certified engines/airframes are maintained more rigorousley. Or make specifically, have more rigorous inspection and check-out procedures after maintenance is performed. Thus, it follows that an engine hanging on an ETOPS airframe may be better maintained and less likely to fail than the same type engine hanging on a non-ETOPS airframe.

You dont have to be a twin to have ETOPS maintenance procedures.

Quoting Chris133 (Reply 31):
That meaning, one engine must be able to get the aircraft into the air even at it's MTOW.

That depends on the runway (MTOW).

Quoting Okelleynyc (Reply 33):
I had no idea that a typical glide ratio on a commercial airliner is around 20:1!

Clean thats about right 18:1 to 14:1...gear down flap 30 on the 744 its about 7:1, flap 20 gear down 7.5:1, flap 10 gear down 8:1
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Starlionblue
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RE: Can A 777/767/757 Fly Only On One Engine?

Thu Mar 02, 2006 2:33 am

Quoting Zeke (Reply 38):
Quoting Starlionblue (Reply 21):
You are correct that a failure in a quad is more likely.

Whilst I would have agreed with you 10-15 years ago when the powerplants on quads were the biggest about, I see them as being more mature now.

Come on Zeke. I continued that with saying that while it is more likely, the odds are still so astronomical one shouldn't worry about it.  Wink

Quoting Zeke (Reply 38):
Quoting Starlionblue (Reply 21):
To answer the original poster, all commercial aircraft (with a few exceptions for singles) must be able to continue take-off after an engine failure and also climb out. On a twin, this means doing it on one. On a quad, this means doing it on three. If you do the math, this means that twins need to be about 50% more powerful than quads, all other things being equal.

Quads are certified for a higher one engine out climb gradient.

Ah good point.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
PanAm747
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RE: Can A 777/767/757 Fly Only On One Engine?

Thu Mar 02, 2006 2:44 am

An interesting side note: It has been discussed here a long time ago about why BA didn't switch its 777 service to 767 service at SAN when it pulled out.

According to the statements at the time, the 777 is the only twin jet in BA's fleet certified to be fully loaded and fully fueled AND take-off from SAN's short runway on just one engine AND clear the terrain (Point Loma). The 767 cannot do this same thing fully fueled and loaded and make it all the way to LHR.

Also, I would think that if a plane loses both engines, technically it is no longer "flying", but "gliding".
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aircanl1011
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RE: Can A 777/767/757 Fly Only On One Engine?

Thu Mar 02, 2006 3:14 am

believe that Boeing did a test on the B777 and flew it for an extended period of time, I believe that it was about six or more hours on one engine.

I realize that you would not do this whilst operating a commercial flight, but it does show that a twin aircraft could fly for an extended time on only one engine.

P.S. I think that new members should be welcomed to the community and not flamed for asking what many consider questions that are ridiculous or have easy answers. If people become afraid to post a thread due to the reaction they may get, A.Net will lose members and will not get new ones. Where will we be then?

I enjoy a good laugh as much as the next guy, but there are ways to include a joke without personally insulting someone and their intelligences. I consider myself a very intelligent person, but there are A.netters that know a lot more about aviation than I do and I enjoy learning from them and having the opportunity to get their input.

just my opinion
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Woodreau
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RE: Can A 777/767/757 Fly Only On One Engine?

Thu Mar 02, 2006 3:29 am

As others have said, transport category aircraft are required to maintain a specified positive climb gradient in the event of an engine failure at Vef.

They are also required to fly one hour in still air with one engine inoperative to a takeoff alternate (for a twin engine aircraft) or fly two hours in still air with one engine inoperative to a takeoff alternate (for 3 or 4-engined aircraft.)

Three or four-engined aircraft are allowed to proceed to their original destination with one engine inoperative if it is as safe as diverting for a precautionary landing.

Quoting Chris133 (Reply 31):
I do know that twin engine planes in the US have to be able to get off the ground on one engine.

This is definitely not true of any aircraft not certified under Part 25 like light twins. The manufacturers are only required to publish a climb gradient. However, it's not required to be positive.
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darkblue
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RE: Can A 777/767/757 Fly Only On One Engine?

Fri Mar 03, 2006 12:19 am

Quoting MD-90 (Reply 10):
Quoting Swank300 (Thread starter):
I have heard that the 747 can fly on one engine if need be.

That one engine will be taking you to the airport, immediately, or to the scene of the crash. A light 747 can stay aloft with only two engines, but not a heavy one. The one engine is needed to power the hydraulics.



Quoting Zeke (Reply 38):
Quoting Swank300 (Thread starter):
I have heard that the 747 can fly on one engine if need be.

Fly yes, maintain altitude no. The windmilling engines will supply hydraulic pressure.

One exception... During GE's flight test of the GE90 on the 747 FTB, they were able to climb out using the GE90 alone. Yeah, okay I know that this is a special case and that no other 747 has flown with a GE90, but pretty cool nevertheless. However, even in this case the other 3 engines were still operating, but pulled back to idle.
 
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Starlionblue
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RE: Can A 777/767/757 Fly Only On One Engine?

Fri Mar 03, 2006 6:13 am

Quoting DarkBlue (Reply 43):
One exception... During GE's flight test of the GE90 on the 747 FTB, they were able to climb out using the GE90 alone. Yeah, okay I know that this is a special case and that no other 747 has flown with a GE90, but pretty cool nevertheless. However, even in this case the other 3 engines were still operating, but pulled back to idle.

Thx for info. But I really think a 747 with 4x GE90 would be a mite overpowered Big grin
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prebennorholm
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RE: Can A 777/767/757 Fly Only On One Engine?

Fri Mar 03, 2006 9:12 am

Quoting Zeke (Reply 38):
Quoting ManuCH (Reply 8):
Other question: how many engines does an A340-B747 need to still be able to operate safely?
2

A quad will thrust wise be able to maintain level flight at very low altitude, but if it is one of the outer engines, then it will experience serious control problems due to extremely asymmetric power.

But due to the drag of the three windmilling engines it will hardly do it until it is rather low on fuel (having dumped excess fuel).

And when gear / flaps are extended, then it will be committed to land.

All turbofan engines produce between 4 and 5 times more thrust at sea level than at typical cruising altitude.

Example, CFM56-5B4 as used on A320s:
Max take-off thrust at sea level: 27,000 lbs
Max climb thrust at 35,000 feet: 5,630 lbs
Thrust reduction factor due to thin air: 4.8

A fully loaded A320 needs roughly 4,000 lbs thrust from each engine (or little more than 8,000 lbs from one engine) to maintain level flight, regardless of altitude.

Some planes climb way beyond 35,000 feet and experience a much higher thrust reduction factor. But that will hardly be quads until they are way into the flight and have burned a lot of the fuel load. Quads always have less total installed power than twins because they lose so much less power with an engine shut down.

If a quad wasn't able to maintain level flight on one engine at low level, at least with considerably reduced fuel load, then it would never be able to climb to cruising altitude.
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cancidas
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RE: Can A 777/767/757 Fly Only On One Engine?

Fri Mar 03, 2006 10:46 am

there is one misconception in this thread though that was brought to my attention by someone outside of the industry. if an aicraft were to lose an engine on the TO roll then they will not be continuing the flight. the reason airplanes are certified to get off the ground on one engine is so that if a failure takes place after V1 they will be able to get off the ground, do a circuit of the airport and land again. that is part of the reason the GE90 is so damn big, they need that much power to get an airplane that heavy off the ground on just one engine.

now, as stated the 747 can fly on just one engine. however, that flight is going to be very very short as it's going to the nearest diversion airport. that one running engine will provide power to hydraulic and electrical systems but not much more.
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zeke
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RE: Can A 777/767/757 Fly Only On One Engine?

Fri Mar 03, 2006 3:25 pm

Quoting Prebennorholm (Reply 45):
A quad will thrust wise be able to maintain level flight at very low altitude, but if it is one of the outer engines, then it will experience serious control problems due to extremely asymmetric power.

I have nothing in my 744 or 343/346 FCOM for driftdown on one engine. I do have two engine driftdown data and two engine landing procedure.

Quoting Prebennorholm (Reply 45):
But due to the drag of the three windmilling engines it will hardly do it until it is rather low on fuel (having dumped excess fuel).

Also the drag from the rest of the airframe, and all that rudder and aileron.

CG position maybe just as important, I would think you going below VMCA on one engine.

Quoting Prebennorholm (Reply 45):
If a quad wasn't able to maintain level flight on one engine at low level, at least with considerably reduced fuel load, then it would never be able to climb to cruising altitude.

I guess we will have to agree to disagree on this, I am not going to go out and try it either.
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Dreamflight767
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RE: Can A 777/767/757 Fly Only On One Engine?

Sat Mar 04, 2006 10:58 am

Quoting TinkerBelle (Reply 20):
Quoting Antiuser (Reply 16):
The whole "4 engines 4 long haul" thing was started by Sir Richard Branson and not Airbus...

Airbus later adopted the quote.

Funny how Airbus adopted this philosophy and to some extent, they demonstrated it with their own a/c (Air Transat A330 glided to the Azores).
 
sccutler
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RE: Can A 777/767/757 Fly Only On One Engine?

Sat Mar 04, 2006 2:22 pm

Quoting Dreamflight767 (Reply 48):
Quoting TinkerBelle (Reply 20):
Quoting Antiuser (Reply 16):
The whole "4 engines 4 long haul" thing was started by Sir Richard Branson and not Airbus...

Airbus later adopted the quote.

Funny how Airbus adopted this philosophy and to some extent, they demonstrated it with their own a/c (Air Transat A330 glided to the Azores).

Again, no relevance; the same circumstances would have left an A340 gliding, as well. The fuel leak vented all available fuel overboard, making the Air Transat A330 graceful-winged glider with RAT-powered flight instruments and controls ("RAT"="Ram Air Turbine," the emergency generating device which cleverly pops out to convert airflow into useful electical power).

I imagine (without knowing at all) that the A330 likely glides a bit better than the A340, if for no other reason than two fewer windmilling engines.
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