A380 Broken Wings
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strong enough to bend
If you cant bend the wing - bend the rule!
@Sunfish - sorry for beeing a skipper, turbulence hits sometimes bcause there are some fency turbs you cant see or simply on long haul they are of considerable extension.
Some jockeys dont like to s****t their pants, PAX too.
best regards and fix
the ship
@Sunfish - sorry for beeing a skipper, turbulence hits sometimes bcause there are some fency turbs you cant see or simply on long haul they are of considerable extension.
Some jockeys dont like to s****t their pants, PAX too.
best regards and fix
the ship
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a380 broken wing
hello sunfish,
tell me why pilots may not talk about structural engineering matters? after all, we sit upfront & have first hand experience how the aircraft behaves in the real world. i agree engineers should design safe aircraft & pilots should fly the the thing safely as well. problems arise if engineers want to fly aircraft & vice versa for the pilots. but that doesn't mean everyone might not express his/her opinion about the matter
for info : designload for public transport aircraft= -1/+2.5g
ultimate load = +50% of designload= -1.5/+3.75g
and fully laden aircraft have & will fly through TS(damn fool pilots that is)
tell me why pilots may not talk about structural engineering matters? after all, we sit upfront & have first hand experience how the aircraft behaves in the real world. i agree engineers should design safe aircraft & pilots should fly the the thing safely as well. problems arise if engineers want to fly aircraft & vice versa for the pilots. but that doesn't mean everyone might not express his/her opinion about the matter
for info : designload for public transport aircraft= -1/+2.5g
ultimate load = +50% of designload= -1.5/+3.75g
and fully laden aircraft have & will fly through TS(damn fool pilots that is)
"wing-bending" thunderstorms
Quote: "If we assume that the A380's positive G rating is +4, then to even reach the design load would require an aircraft to do something like flying through a thunderstorm at absolute max gross."
Sunfish, A380's will fly thru thunderstorms, sooner or later all planes do. Not on purpose, but for one reason or other.
And about wing-bending moment; I'd rather to be at "absolute max gross". All that fuel in the wings will help reduce the wingbending moment.
Sunfish, A380's will fly thru thunderstorms, sooner or later all planes do. Not on purpose, but for one reason or other.
And about wing-bending moment; I'd rather to be at "absolute max gross". All that fuel in the wings will help reduce the wingbending moment.
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This world is absolutely nuts.
If my pass score for a test is 75% I fail if I score 74%.
Not only would I be axpected to read a few more pages which -in theory- should give me the required 75%; I would be forced to redo said test!
So tell why it is more important to score a theoretical test within limits then to have a structure of an aircraft keep it up to the limits?
Explain that one to the "Daily Mail" after the first failure of a wing with pax on board..
If my pass score for a test is 75% I fail if I score 74%.
Not only would I be axpected to read a few more pages which -in theory- should give me the required 75%; I would be forced to redo said test!
So tell why it is more important to score a theoretical test within limits then to have a structure of an aircraft keep it up to the limits?
Explain that one to the "Daily Mail" after the first failure of a wing with pax on board..
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It΄s all too theoretical 
.... This 150 % bending aplied smoothly and with a careful increase in intensity is surely a have to have test, but it isn΄t the proper simulation of flying through a TS.
I guess that other tests like constant vibration with short & harsh jolts over longer periods of time have been made and were succesful. Tests like these will determine the actual durability of the wing.
But does anyone know if these 150 % are an industry standard by Airbus, or if it is an actual JAA/FAA requirement?
.... This 150 % bending aplied smoothly and with a careful increase in intensity is surely a have to have test, but it isn΄t the proper simulation of flying through a TS.I guess that other tests like constant vibration with short & harsh jolts over longer periods of time have been made and were succesful. Tests like these will determine the actual durability of the wing.
But does anyone know if these 150 % are an industry standard by Airbus, or if it is an actual JAA/FAA requirement?
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Will the FAA require them to crack another or force a reduction in ZFW, being as the failure point was outside the allowed margin ?
And I Just wanted to say...........
Many headlines make it seem as though the wing test was a complete failure and the stories don't mention the fact that the wing was supposed to break.
Even though Airbus is so
secretive, when official news does reach the light of day, the media always makes such a sensation with grossly misleading headlines.
This kind of crap reporting doesn't happen with Boeing in the development stages - they tend to get picked on later. (for whatever reason)
And I Just wanted to say...........
Many headlines make it seem as though the wing test was a complete failure and the stories don't mention the fact that the wing was supposed to break.
Even though Airbus is so
secretive, when official news does reach the light of day, the media always makes such a sensation with grossly misleading headlines. This kind of crap reporting doesn't happen with Boeing in the development stages - they tend to get picked on later. (for whatever reason)
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Sunfish - whats wrong with Engineers talking about structual failure? I am one. I happen to be a Pilot too.
Airliners are not designed to 4g, the usual limits are what has been stated above.
The fact is that the 150% is an aim and the wing failed that aim. Certification requirements are there for many reasons - and this wing didn't make it. As I said above though, it could be a simple fix, or indeed something much more serious. We are not saying the A380 wings will fail in light turbulence, or even in a TS. What we are saying is that the aircraft hasn't met the requirements - the reason for this is unclear and so the ramifications of that are unknown. Could it be that the aircraft will fail in a TS one day after 20 years of service, or could it be that the failure is easily fixable and nothing to worry about? For your info, severe turbulence can be encountered without warning, in clear air and have a very sudden onset - its not just about TS.
Superpilut - your analogy is a bit too simplistic. Structural Engineering is a bit more complicated than answering a few questions on a piece of paper. It depends why you failed the test. A good examiner will write an exam that tests all your areas of knowledge - if got your 74% by demonstrating good knowledge of all but one of your subject areas, you may only be re-tested on the one you failed. Do you see the difference?
Daily Mail readers - well you just can't explain to them, that's half the problem!
Airliners are not designed to 4g, the usual limits are what has been stated above.
The fact is that the 150% is an aim and the wing failed that aim. Certification requirements are there for many reasons - and this wing didn't make it. As I said above though, it could be a simple fix, or indeed something much more serious. We are not saying the A380 wings will fail in light turbulence, or even in a TS. What we are saying is that the aircraft hasn't met the requirements - the reason for this is unclear and so the ramifications of that are unknown. Could it be that the aircraft will fail in a TS one day after 20 years of service, or could it be that the failure is easily fixable and nothing to worry about? For your info, severe turbulence can be encountered without warning, in clear air and have a very sudden onset - its not just about TS.
Superpilut - your analogy is a bit too simplistic. Structural Engineering is a bit more complicated than answering a few questions on a piece of paper. It depends why you failed the test. A good examiner will write an exam that tests all your areas of knowledge - if got your 74% by demonstrating good knowledge of all but one of your subject areas, you may only be re-tested on the one you failed. Do you see the difference?
Daily Mail readers - well you just can't explain to them, that's half the problem!
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a380 broke
hello everyone
it is the first time since long that a new project of that size failed such an important & spectacular structural test. but, then, when was it the last time? i sadly remember the comet story.
it is the first time since long that a new project of that size failed such an important & spectacular structural test. but, then, when was it the last time? i sadly remember the comet story.
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Originally Posted by Charly
It΄s all too theoretical .... This 150 % bending aplied smoothly and with a careful increase in intensity is surely a have to have test, but it isn΄t the proper simulation of flying through a TS.
I guess that other tests like constant vibration with short & harsh jolts over longer periods of time have been made and were succesful. Tests like these will determine the actual durability of the wing.
But does anyone know if these 150 % are an industry standard by Airbus, or if it is an actual JAA/FAA requirement?
.... This 150 % bending aplied smoothly and with a careful increase in intensity is surely a have to have test, but it isn΄t the proper simulation of flying through a TS.I guess that other tests like constant vibration with short & harsh jolts over longer periods of time have been made and were succesful. Tests like these will determine the actual durability of the wing.
But does anyone know if these 150 % are an industry standard by Airbus, or if it is an actual JAA/FAA requirement?
I'm in partial support of Sunfish on this. This is a complex subject which goes far beyond simple structural engineering discussions and involves judgements within the whole basis of the actual regulations themselves, of how much, how often compared to all the other competing risks to flight.
Most of the preceeding discussion are of a brevity that leads for lots of misunderstanding between posters.
In my opinion, you really can't do justice to a reasoned discussion simply using a keyboard driven forum.
I don't mean to abort this discussion but only to caution against simple conclusions for or against since clearly all the facts (rule intent and design intent) are not in evidence.
Most of the preceeding discussion are of a brevity that leads for lots of misunderstanding between posters.
In my opinion, you really can't do justice to a reasoned discussion simply using a keyboard driven forum.
I don't mean to abort this discussion but only to caution against simple conclusions for or against since clearly all the facts (rule intent and design intent) are not in evidence.
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a380 wing break
iomapaseo,
it is simple: the thing failed a mandatory certification hurdle. noel says he will not break a new wing, therefore lobbying, computor modelling & untried beefing up solutions will be in the order of the day. american alligators(lawyers) are already in the starting blocks for the day that it will suffer a major break up(heaven forbid, i hope, if there is one).
it is simple: the thing failed a mandatory certification hurdle. noel says he will not break a new wing, therefore lobbying, computor modelling & untried beefing up solutions will be in the order of the day. american alligators(lawyers) are already in the starting blocks for the day that it will suffer a major break up(heaven forbid, i hope, if there is one).
I remember seeing a series of television programmes on the 777, in one of which they showed the wing tested to destruction by application of hydraulic rams across the surface. From memory, the test criteria was 1.5 x design load, so this is a standard number. The load was applied slowly.
I would suggest the issue of tolerances, live versus static loads, accuracy of computer models etc. is the reason for the 1.5 factor. This is a considerably higher factor of safety than is applied to other structures which are not tested (such as support structures for deepwater oil production platforms).
I would suggest the issue of tolerances, live versus static loads, accuracy of computer models etc. is the reason for the 1.5 factor. This is a considerably higher factor of safety than is applied to other structures which are not tested (such as support structures for deepwater oil production platforms).
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From time to time you see reports about various airliners being offered with an incrreased ZFW, as part of a package of improvements to its performance. Does the discussion here suggest that:
a) they test a new wing to destruction to satisfy the 150% rule, or
b) the original wing was tested to a higher level (say 160%), and so the new ZFW still falls within range?
Apologies if I am merely demonstrating that a little knowledge is a dangerous thing, but it's been bugging me!
a) they test a new wing to destruction to satisfy the 150% rule, or
b) the original wing was tested to a higher level (say 160%), and so the new ZFW still falls within range?
Apologies if I am merely demonstrating that a little knowledge is a dangerous thing, but it's been bugging me!
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Hello all, Sunfish especially.
OK, let us clarify some things related to certification:
Limit loads = the maximum loads to be expected in service - FAR 25.301 (a)
Ultimate loads = limit loads multiplied by prescribed factors of safety - FAR 25.301 (a)
Factor of safety = 1.5 (unless stated otherwise) - FAR 25.303
therefore:
Ultimate load = 1.5 x limit load
There are no Design Loads defined in certification documents.
In order to release the first FTA (Flight Test Article) to start flying, usually, CAA responsible for certification asks for completion of a batch of limit loads tests.
It is up to CAA to define, according to the relevant regulations and its judgment, which tests are required.
For the completion of certification process all the ultimate loads tests have to be satisfactorily completed. It is up to CAA, again, and the responsible party (OEM) to agree on what has to be done if there is some unacceptable test result (Margin of Safety < 0).
That can be a repeated test, a change in FEM, a weight penalty or whatever they agree on. It is FLEXIBLE.
As for the statement that structure is fail-safe this is wrong since this concept was left in early 70s with introduction of Damage tolerant structure.
Last fail safe model was 747.
Cheers
OK, let us clarify some things related to certification:
Limit loads = the maximum loads to be expected in service - FAR 25.301 (a)
Ultimate loads = limit loads multiplied by prescribed factors of safety - FAR 25.301 (a)
Factor of safety = 1.5 (unless stated otherwise) - FAR 25.303
therefore:
Ultimate load = 1.5 x limit load
There are no Design Loads defined in certification documents.
In order to release the first FTA (Flight Test Article) to start flying, usually, CAA responsible for certification asks for completion of a batch of limit loads tests.
It is up to CAA to define, according to the relevant regulations and its judgment, which tests are required.
For the completion of certification process all the ultimate loads tests have to be satisfactorily completed. It is up to CAA, again, and the responsible party (OEM) to agree on what has to be done if there is some unacceptable test result (Margin of Safety < 0).
That can be a repeated test, a change in FEM, a weight penalty or whatever they agree on. It is FLEXIBLE.
As for the statement that structure is fail-safe this is wrong since this concept was left in early 70s with introduction of Damage tolerant structure.
Last fail safe model was 747.
Cheers
Hardly Never Not Unwilling
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I don't like the logic of 'When will you ever go through a thunderstorm at max gross weight?'
These aircraft will fly for decades and will age through the process of thousands of pressurization cycles, firm landings, and wing flexes. Their initial structural strength will deteriorate over time. Initial certification testing's purpose is to assure structural integrity over the design life of the aircraft.
Design tests are mandated to prove the design concept under actual physical stresses. This isn't a Boeing vs. Airbus issue, but one of aviation safety.
These aircraft will fly for decades and will age through the process of thousands of pressurization cycles, firm landings, and wing flexes. Their initial structural strength will deteriorate over time. Initial certification testing's purpose is to assure structural integrity over the design life of the aircraft.
Design tests are mandated to prove the design concept under actual physical stresses. This isn't a Boeing vs. Airbus issue, but one of aviation safety.
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Please pardon (again) my ignorance. I understand that the +50% factor
imposed by the regulations may be somewhat arbitrary. What is actually done to confirm or revisit this number as a reasonable safety margin?
How close are real dynamic situations (turbulence encounters) to the static loads which are imposed during the ground tests?
imposed by the regulations may be somewhat arbitrary. What is actually done to confirm or revisit this number as a reasonable safety margin?
How close are real dynamic situations (turbulence encounters) to the static loads which are imposed during the ground tests?
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Safety Factor, is a multiplier applied to the calculated maximum load to which a component or assembly will be subjected. Thus, by effectively "over engineering" the design by strengthening components etc
..
Aerospace engineering where safety factors can be as low as 1.10 or 1.25 (in extreme cases like unmanned vehicles) or more typically 1.50, are relatively low because the costs associated with structural weight are so high. This low safety factor is why Aerospace parts and materials are subject to much more stringent testing and quality control ..
One can easily design an Aircraft with for example, a safety factor of 5.00 .. PAS loads would be amazingly low .. fuel consumption extremely high and range well below needs . Probably impractical .
The 380 tests being so close to the design objective of 1.50 is rather impressive if one thinks about it .. its just a pity it is slightly below target rather than on or just above ,,,,
Aerospace engineering where safety factors can be as low as 1.10 or 1.25 (in extreme cases like unmanned vehicles) or more typically 1.50, are relatively low because the costs associated with structural weight are so high. This low safety factor is why Aerospace parts and materials are subject to much more stringent testing and quality control ..
One can easily design an Aircraft with for example, a safety factor of 5.00 .. PAS loads would be amazingly low .. fuel consumption extremely high and range well below needs . Probably impractical .
The 380 tests being so close to the design objective of 1.50 is rather impressive if one thinks about it .. its just a pity it is slightly below target rather than on or just above ,,,,
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Please excuse a question from an unqualified person, but I'm struggling with the basic concepts of this thread. If something is tested, against an established pass mark, and then fails that test, then it has failed to pass. The test can be re-taken, in the hope of meeting or exceeding the pass mark, but until the pass mark is achieved, it is not a pass: Surely, what shouldn't happen is that a negotiation takes place as to the validity of the pass mark, or a pass is awarded on the basis of a promise of future work and improvement?
Clearly I'm missing something - maybe my view is simplistic? I would appreciate clarification...
Clearly I'm missing something - maybe my view is simplistic? I would appreciate clarification...
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TightSlot:
It does go more or less along the lines I have already posted.
You do get a result based on the initial set of assumptions.
If you do not have the good result you change the assumptions.
One thing you can change is your model (FEM = finite element model - the "wire" model that in specialized software (FE) simulates the structure exposed to conditions it will see in flight).
The closer are your simulated results to tests the better it is. If you are close on the lower side that gives you few options:
1) Change the model so it can better represent the real conditions
2) Declare a weight penalty (ouch!) and pay the price
3) Reinforce the failed part of the structure and redo the test (tooooooo expensive)
Also a certain level of "convincing" and political approach is always present. All this rules can be interpreted in different way. What I quoted before from CFAR 25 is just a small portion of all that has to be satisfied in order for an aircraft to get its CofA (certificate of airworthiness).
it is up to a local CAA (regulatory body) to make that decision.
Therefore, it is not a straight yes or no answer.
It does go more or less along the lines I have already posted.
You do get a result based on the initial set of assumptions.
If you do not have the good result you change the assumptions.
One thing you can change is your model (FEM = finite element model - the "wire" model that in specialized software (FE) simulates the structure exposed to conditions it will see in flight).
The closer are your simulated results to tests the better it is. If you are close on the lower side that gives you few options:
1) Change the model so it can better represent the real conditions
2) Declare a weight penalty (ouch!) and pay the price
3) Reinforce the failed part of the structure and redo the test (tooooooo expensive)
Also a certain level of "convincing" and political approach is always present. All this rules can be interpreted in different way. What I quoted before from CFAR 25 is just a small portion of all that has to be satisfied in order for an aircraft to get its CofA (certificate of airworthiness).
it is up to a local CAA (regulatory body) to make that decision.
Therefore, it is not a straight yes or no answer.
Last edited by Grunf; 15th Mar 2006 at 22:14.