Airbus A318-A380
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Airbus A318-A380
I have been reading alot about Airbus aircraft lately and found out that the throttle levers are not connect to the engines themselves but to a computer unit , now this is where the question comes in , if there is a fire or a explosion and all the instruments and computers no longer work , how would you get down on the ground safely as you wouldn't be able to control the engines.
There is a lot of back up, no single failure on a public transport spec aircraft can be catastrophic. Anyway a conventional control could be damaged. Maybe it might help you understand if you read up on some of the basics and then airbus technology later so you understand the thinking behind it. Not meaning to put you down but the question is a little simplistic if still valid.
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Hey VvG,
The discussion is about mechanical or digital connection between thrust levers and engines.
not between flightcontrols and control column
Groeten FT
The discussion is about mechanical or digital connection between thrust levers and engines.
not between flightcontrols and control column
Groeten FT
Last edited by Flying Torquewrench; 4th Jan 2007 at 18:25. Reason: typo
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Clarence,I'm not an engineer,and that info is not in my FCOM,so..but I am 99% sure..
And it doesn't matter to me how the connection is made,I won't start to dismantle the thing.Only thing I want is that the thrust will change when I move the thrust levers.
VVG: i got beat by FT on that . And yes,I've been,a total of around 200 days flight time.
And it doesn't matter to me how the connection is made,I won't start to dismantle the thing.Only thing I want is that the thrust will change when I move the thrust levers.
VVG: i got beat by FT on that . And yes,I've been,a total of around 200 days flight time.
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From the dark and distant days that i was a ground engineer i mean to remember that the B737 classic has a mechanical connection between thrust levers and engine (HMU).
While (as said before) the B737NG has no mechanical connection between thrust levers and engine (FADEC)
So i am sorry B737fan but you got no ground on which you can start an Airbus bashing
FT
While (as said before) the B737NG has no mechanical connection between thrust levers and engine (FADEC)
So i am sorry B737fan but you got no ground on which you can start an Airbus bashing
FT
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Alex,
I was not having a go at you, but rather at those making your FCOM. Shouldn't you be 100% certain at how the throttles are connected to the engines? Is it electrical, is it mechanical or a combination? Does it make a difference whether the electrical or mechanical input is used if it's a combination?
Uncertainty leaves room for misconceptions and misinterpretations. Which again leads to....
I trust you understand what I am getting at.
I was not having a go at you, but rather at those making your FCOM. Shouldn't you be 100% certain at how the throttles are connected to the engines? Is it electrical, is it mechanical or a combination? Does it make a difference whether the electrical or mechanical input is used if it's a combination?
Uncertainty leaves room for misconceptions and misinterpretations. Which again leads to....
I trust you understand what I am getting at.
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Hy Clarence.
Many years ago I flew some russian types airplanes.They had a habit of teaching you everything,a pilot could have actually dismantle the plane piece by piece.You had to know any bolt,screw,cable..It was a nightmare.A lot of info,that one would forget in less than a year.
You have to kow many things as a pilot.Knowing every bit of your plane won't help you so much,and won't get in you're head.Imagine a 747,or a 380...
You have to know systems,how they work,etc...But to know in detail,well,it's another thing
I know what the thrust lever do,when moved...how they do it ,it doesn't matter so much.
If I move them,and nothing happens,then go to the QRH,and resolve the relevant case. I won't get my screwdriver,and fix the thing..
I understand your point,but it's the same with cars,for ex.You can safely drive your car,know what the ABS do,or the ESP,use them perfect.But do you know how are those systems made,or how it transmit the info's to the car computer,etc..Get my point?
And ,btw, the signal from the thrust levers is electrically transmited to the MEC,even on the 737 efis.
Brgds
Alex
Many years ago I flew some russian types airplanes.They had a habit of teaching you everything,a pilot could have actually dismantle the plane piece by piece.You had to know any bolt,screw,cable..It was a nightmare.A lot of info,that one would forget in less than a year.
You have to kow many things as a pilot.Knowing every bit of your plane won't help you so much,and won't get in you're head.Imagine a 747,or a 380...
You have to know systems,how they work,etc...But to know in detail,well,it's another thing
I know what the thrust lever do,when moved...how they do it ,it doesn't matter so much.
If I move them,and nothing happens,then go to the QRH,and resolve the relevant case. I won't get my screwdriver,and fix the thing..
I understand your point,but it's the same with cars,for ex.You can safely drive your car,know what the ABS do,or the ESP,use them perfect.But do you know how are those systems made,or how it transmit the info's to the car computer,etc..Get my point?
And ,btw, the signal from the thrust levers is electrically transmited to the MEC,even on the 737 efis.
Brgds
Alex
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Throttle Resolvers
Folks, apologies if I'm preaching to the choir here, but as I read the original question, it implied to me that the OP thought there was a digital signal going between the throttle quadrant and the FADEC. (I may be reading the question wrong - if so feel free to ignore the rest...)
I found this gem in the transport canada report into SR111:
"The FADEC receives inputs from the engine throttle resolvers located below the central pedestal on the throttle levers. There is a dual-throttle resolver per thrust lever. The dual resolver contains two resolvers in one package driven by a single, common shaft. One resolver provides TRA input to Channel A and the second to Channel B. The FADEC provides electrical excitation for the resolvers."
Generally, there is a permanant magnet alternator on the accessory drive gearbox which powers the fadec once you get the HP spool speed about some fairly low value. So as long as the engine is lit and nothing has snapped the wires between the throttles and the engine, move the lever and the engine will get the signal that you want something to change.
Hope that helps a little
I found this gem in the transport canada report into SR111:
"The FADEC receives inputs from the engine throttle resolvers located below the central pedestal on the throttle levers. There is a dual-throttle resolver per thrust lever. The dual resolver contains two resolvers in one package driven by a single, common shaft. One resolver provides TRA input to Channel A and the second to Channel B. The FADEC provides electrical excitation for the resolvers."
Generally, there is a permanant magnet alternator on the accessory drive gearbox which powers the fadec once you get the HP spool speed about some fairly low value. So as long as the engine is lit and nothing has snapped the wires between the throttles and the engine, move the lever and the engine will get the signal that you want something to change.
Hope that helps a little
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And what is a B737 classic. I see its got a HMU so it can't be a B737-200. (Now that is a classic aircraft!)
Anyway the B737-400 has an efis, and it has CFM56-3 engines which have big mechanical HMU fuek control units and no FADEC.
It has a big steel cable going out to the engine.
Perhaps your B737efis had CFM56-7 engines with a fadec and electric wires, but mine has steel cables.
A good guide is that if it has a FADEC then it has electric wires.
But it gets muddied with RR.
The RB211-535 has steel cables
The RB211-524G (B747-400) has electric wires, but no FADEC!
Now the B767 can have either steel cables or electric cables depending on the engines.
Just to confuse.
But I am still confused over the term B737 classic.
If this is a B737-300 (with or without efis), then what do we call a B737-200?
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This thread is getting so vague that I dont know if we are talking about the 200 300 400 or NG.
Anyway the 400 had two switches above the P3 seat that switched off the performance management computer but the engines were still connected via the FADEC, or was that the 300?. As far as I am aware if you had a total electrical failure then the engines continued to turn so the FADEC/PMC was more for fine tuning than an absolute necessity.
I don't know how the NG is connected but if we get back to the basic question, how do you get back on the ground if the engines are out of control? I don't know the scenario he has in mind but don't forget that pulling the fire handles on a 737 will still shut off the fuel and the engines will shut down. I know it is not an ideal plan but if all else fails then it might help to get the aircraft down given a long enough runway and a lot of luck. Perhaps if the questioner can be more specific then he may get a better answer.
Anyway the 400 had two switches above the P3 seat that switched off the performance management computer but the engines were still connected via the FADEC, or was that the 300?. As far as I am aware if you had a total electrical failure then the engines continued to turn so the FADEC/PMC was more for fine tuning than an absolute necessity.
I don't know how the NG is connected but if we get back to the basic question, how do you get back on the ground if the engines are out of control? I don't know the scenario he has in mind but don't forget that pulling the fire handles on a 737 will still shut off the fuel and the engines will shut down. I know it is not an ideal plan but if all else fails then it might help to get the aircraft down given a long enough runway and a lot of luck. Perhaps if the questioner can be more specific then he may get a better answer.
Last edited by Seat1APlease; 6th Jan 2007 at 23:17.
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Original or Jurassic are the -100 and -200 series, Classic is -300 to -500 and NG is -600 to -900 series.
That said the classic doesn't have a FADEC normally. It is controlled by a hydromechanical MEC unit and a PMC (Power Management Control) unit. The PMC is indeed an electronic system but has only limited authority over the MEC, it uses power lever angle, N1 and inlet temperature and pressure to adjust (or trim) the desired N1, to do that it adjusts fuel flow as a function of thrust lever angle. However the PMC can only fine-tune N1, for general settings the MEC is used which is as far as im aware mechanicaly linked to the power (or thrust) levers. In the case of an PMC failure you still can control your thrust with the power levers (via the MEC), just have to be a bit more cautious about big changes in thrust.
That said the classic doesn't have a FADEC normally. It is controlled by a hydromechanical MEC unit and a PMC (Power Management Control) unit. The PMC is indeed an electronic system but has only limited authority over the MEC, it uses power lever angle, N1 and inlet temperature and pressure to adjust (or trim) the desired N1, to do that it adjusts fuel flow as a function of thrust lever angle. However the PMC can only fine-tune N1, for general settings the MEC is used which is as far as im aware mechanicaly linked to the power (or thrust) levers. In the case of an PMC failure you still can control your thrust with the power levers (via the MEC), just have to be a bit more cautious about big changes in thrust.
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Is there any way to get manual control of the engines over the automatics the Airbus? I.e. - can the autothrottle/TOGA/Open/Flex etc sytems be cancelled so that the movements of the thrust levers have a more direct effect on the thust (albeit through the FADEC); like on older aircraft where autothrottles could be disengaged with a 'click'?