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Thread: A380 having a cracking time

  1. #31
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    Just to comment on PeeDee's pic, I've been told that the wrinkles on B52 fuselages are intentional and allow for a certain amount of flex in the fuselage. Apparently the wrinkles are there from new and don't just develop.
    Adler Tag ("Eagle Day") 13th August 1940

  2. #32
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    The fact that both the A380 wing cracks and the DC-10 accidents involve airliners is about all they have in common. If this news item about the A380 reminded you of the DC-10 accidents then I suspect you are very probably alone in making the connection.

    The wrinkles on a B-52 are called a Wagner tension field.
    So much for Pathos

  3. #33
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    PeeDee..the wrinkles on a B-52 don't have anything to do with fatuigue.
    So mentioning them in the current discussion is a bit of a misnomer.
    And I'll repeat, I don't think the B-52s have ever been resparred...even for a SLEP.
    There are two sides to every story. The truth is usually somewhere between the two.

  4. #34
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    [QUOTE=paul178;1855909]Just suppose you had enough money to buy a Bugatti Veyron and it developed cracks in it all singing and dancing spoiler. On mentioning it to the supplier you were told "Its quiet safe no cars crashed due to it yet" Would you say "Ok then" and bimble off?

    Yep, for a Veyron, I would give them my dogs B******s
    Not mine though.
    Jim.

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    There is no such thing as a problem, just a solution!!

  5. #35
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    Re 32

    Both examples are regretfully symptomatic. Your dismissal of the potential for an excess of human misery, death and possibly widespread destruction is unworthy.

    Aircraft design and construction is an endeavour that requires the very best of the continuous application of unrelenting skill and expertise. Nothing less in that industry can be tolerated. Aviation engineering standards have to be of the very highest.

    John Green

  6. #36
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    Quote Originally Posted by Mr Creosote View Post
    I think the notion of the DC-10 having crack problems stemmed (unjustly) from the American Airlines crash in 1979, when an engine fell off shortly after take-off. American's maintenance procedures -mainly in using a forklift truck to change engines- was held largely responsible,
    Yup, I know someone connected with this & it was the way the engine was lifted up onto the mounts over stressed one of them causing it to later fail leaving an engine shaped dent in the planet (basically).

    & to this day Douglas aircraft are refered to as "Longbeach Death Tubes"
    If anybody ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me: It's all balls. RJM.

  7. #37
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    Cool

    Quote Originally Posted by Ritch & Max View Post
    Hi all

    Untill a few weeks ago, I worked for the company, based in Nottinghamshire who manufacture the parts concerned.

    The wing rib is a very large one piece vertical web, with lighteneing holes, vertical and horezontal stiffeners etc all machined into the rib, also machined in are the web feet, which are basicaly angled brackets (cleats) machined to fit between stiffeners (stringers) machined into the top and bottom wing skins. The feet are then attached with mechanical fasteners to the wing skins to form the wing assembly.

    If the feet should for any reason shear, then the skins are no longer attached to the ribs, simple as that. And with a wing full of a large weight in fuel, it is a very serious situation.

    There are answers to both improvments to new wings and ways to repair the existing ones. There have been big changes at the manufacturer concerned, including top managment changes. But that is about all I can say without risk of legal action.
    Very interesting and enlightening information obviously your knowledge and experience gives grounds for very informed comment but I would just say be a little cautious on how much detail you give .As you say to much knowledge at times can generate litigation.
    But very interesting detailed info I wonder how they go about dealing with what on the surface sounds more than a normal expected run of the mill maturing problem within the airframe design.

    I wonder if anyone knows is the A380 wing a complete new animal or is it a uprated version of an existing Airbus wing. I would suspect that the wing is an all new animal but manufacturers have been known to modify off the shelf items.

    Mike E

  8. #38
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    Quote Originally Posted by John Green View Post
    Re 32

    Both examples are regretfully symptomatic. Your dismissal of the potential for an excess of human misery, death and possibly widespread destruction is unworthy.
    Dismissal? Unworthy? Really? Staggering.....

    As they say on Dragon's Den "I'm out"
    So much for Pathos

  9. #39
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    Part of an article from the 'Airpower' website (1978)

    Wings do many things. Their first purpose, of course, is to provide aerodynamic lift to get the aircraft off the ground; but they also carry heavy engines, bombs, and fuel pods. Still others carry undersigned-for external ordnance. One other common thing these all important wings do is get tired and fatigued and many times they develop dangerous cracks. Sometimes it happens much sooner than predicted. The Air Force has examples of each type. The first is the venerable 15- to 20-year-old B-52 and, surprisingly the relatively new C-5A.

    The oldest of the giant eight-engined bombers still flying, the B-52D, was one of the most numerous of the giant Stratofortresses built. Extensively used in Vietnam, many of these late 1950s versions were sporting well over10,000 flight hours although they were originally designed for only half that number. In 1971, the planned phase-out year for the D-birds, the Air Force decided that the aircraft would be needed much longer. But something had to be done--and in a hurry, since the aircraft were showing their age, large structural cracks appearing with increasing regularity. So it was decided that a portion of the B-52D fleet would get a sizable face lift.

    Starting in the mid-1970s, 80 of the D-birds were extensively modified by Boeing, the last modifications completed in February of 1977. These modifications entailed the scrapping of about 15 tons of parts from each aircraft. Then new leading edges and stiffeners were provided. wings were partially reskinned, wing pylons modified, and the fuselage partly reskinned at the wing root. The program, called Pacer Plank, resulted in a price tag of $2.6 million per copy--a large percent of the original cost of the aircraft when it was built two decades earlier.

    In the modification process, Boeing removed the wings from the fuselage and worked on the fuselage and wings separately. Following modification, wings and fuselage were rejoined, tested, and sent on their way.

    A surprising phenomenon resulted from the Pacer Plank modifications. The new wing skin is much cleaner aerodynamically than the skin it replaced, resulting in considerably less drag. Even though the modified plane weighs about 3400 pounds more, its cruise range has been increased by three percent. After three decades, this aircraft is getting older, but she is also getting better.

    The later G and H models are also undergoing structural changes, although not as extensive as those on the B-52D* Not to be forgotten are the 615 KC-135 tankers that are also undergoing wing modifications to stretch their operational lifetime into the 1990s.

    * "USAF is considering the use of winglets on its Boeing B-52Gs. The modification would not only enhance aerodynamic performance of the bomber, earmarked as the air-launched cruise missile carrier, but also would provide distinctive markings…of those B-52G models used for cruise missiles and thus avoid having all B-52s counted as potential carriers of this weapon." (Aviation Week & Space Technology, March 6,1978, p. 9).

    But wing problems certainly have not been restricted to 20-year-old airplanes. The relatively new C-5 transport fleet is also having its problems. The first indication of C-5 wing structural deficiencies occurred in July1969, when the wing root failed in static test at 126 percent of design limit load. Then, in January1970, cracks in the rear beam cap of the third C-5A built were discovered.

    The Air Force Scientific Advisory Board (SAB) was convened in February 1970, to review the C-5 structural failures and plan corrective actions. However, by this time, the fortieth airplane was in final assembly, and major wing parts were already machined for the sixtieth article. It was clearly impractical to incorporate in production a major redesign for improved fatigue life.

    So, in 1975, the Air Force awarded a $28,454,000 contract to Lockheed for design of a modification to the C-5A wing. The wing modification involved redesign of the center, inner, and outer wing boxes. The existing leading and trailing edge structures, as well as all wing subsystems, were retained. It was hoped that these changes, coupled with the use of an improved wing material with better fracture toughness characteristics, would ensure a long life wing. The design contract awarded in 1975 was the first phase in a four-phase program and covered the necessary engineering analyses and tests to define the modification details.

    The second phase of the modification program called for fabrication of two kits of new wing sections and associated hardware. A C-5 fuselage (ground test article) outfitted with one "kit" would receive extensive fatigue testing. The second wing kit will be installed on a selected C-5A aircraft and flight tested at the Air Force Flight Test Center in the fall of 1980. If approved Phase III, the production of wing modification kits, would be initiated in early 1980. Installation of the wing modification on the remaining C-5 force (76 aircraft) would begin in early 1982 and would constitute Phase IV of the program. The aircraft would be modified at a rate of 1.5 per month, with a downtime of eight months.

    As part of Phase IV, an Active Lift Distribution Control System will be reinstalled on the C-5 wing as a fuel conservation measure. It is estimated that this system, which automatically reduces wing loads in flight will save six million gallons of fuel per aircraft over a period of 30 years, based on current usage rates.
    The C5 info is probably more akin to the 380 thread...

    Large flexible wings are always going to crack somewhere,perhaps a little early for 380's do do so but as I said previously until we know the exact problem we cannot really meaningfully discuss it,a few minutes googling will find wing crack info on a/c you thought were built like a brick 'outhouse'

  10. #40
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    Quote Originally Posted by J Boyle View Post
    Not quite. Though metal fatigue was new to aircraft, what doomed the early Comets was fatigue brought on by pressure.
    Those dangers were understood as far back as the 1860s...that's why boilers are round as are their inspection ports.
    According to RAF pilot and aviation engineer turned author, Bill Gunston, the Comet losses were totally preventable.
    I agree with you on the comet problems John
    The fuselage was badly designed,the structure/skin was far too light and exacerbated by poor workmanship !
    According to one of our forum members on here -DH did not have a proper stressing dept at that time,and I believe that.
    DH a/c did have a reputation in the USA for structural weakness.
    I read an autobio years ago (cannot remember author) and he was shocked at being able to 'oilcan' an early Comet skin on a double curvature area...he was flying the things at that time !!

    rgds baz

  11. #41
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    Quote Originally Posted by J Boyle View Post
    PeeDee..the wrinkles on a B-52 don't have anything to do with fatuigue.
    So mentioning them in the current discussion is a bit of a misnomer.
    And I'll repeat, I don't think the B-52s have ever been resparred...even for a SLEP.
    The wrinkles is just another interesting point about structural movements. It wasn't meant as a comparison.
    I bow to your better memory on B-52. Having read the post on he C5, maybe it was that which was stuck in my head.

    As for the wrinklles being intentional and there from new. Can't buy that one. The movement allowables are intentional, the wrinkles are a consequnce of it. If they were built in, they would be a uniformed pattern that was manufacturable.
    Higher than Gods, in Concorde or a Mozzy.

  12. #42
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    Here's the latest from Aviation Week magazine...

    A380 Wing Rib-Feet Fix to Cost 'Quite Some Money'
    Posted by Robert Wall at 2/14/2012 12:26 PM CST


    Although Airbus does not put a dollar figure on cost of inspecting and fixing the A380 fleet because of a wing component flaw, company CEO Tom Enders concedes it will be “quite some money.”
    Airbus is taking full blame for the situation. The problem “we created ourselves and are fixing ourselves,” Enders says during the Singapore air show.

    It is not just about the here and now, though. Enders says the situation has sparked an in-depth review to assess why the company's design and engineering system did not catch the potential for the manufacturing flat early. “Are we learning from this for other programs? Absolutely,” Enders stresses.

    At issue is an A380 fleet-wide inspection, mandated by the European Aviation Safety Agency, to inspect and potentially fix L-shaped wing rib-feet which have experienced cracks. The airworthiness directive calls for aircraft with fewer than 1,216 flight cycles to undergo the inspection when they reach 1,300 flight cycles or before; for those between 1,216 and 1,384 flight cycles the inspection has to be completed within six weeks or 84 flight cycles or six weeks, and those with 1,384 flight cycles or more within three weeks.
    There are two sides to every story. The truth is usually somewhere between the two.

  13. #43
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    Cool

    That does go to show that the intial suggestions where correct it is a design flaw and totally unexpected.The comment it is going to cost a fair amount to fix seems to suggest that someone lost the ball on this one.It also seems to imply that its not just a simple fix and could mean a good bit of down time per airframe to fix ,perhaps our friend Rich and Max with experience from the manufacture side of these components could give some insight as to where on the rib structure this attachment foot goes and how many are actually in each wing.

    With this being made official and the first real statement from the company and taking place at the Singapore airshow it surely cant do the Airbus syndicate any good against its major rival Boeing who must be making I would imagine big play of these major teething problems with their major competitors aircraft and with all the other production issues must have an unfortunate negative affect on sales ??

    Mike E

  14. #44
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    Firebex


    As I pointed out in previous comments on this topic, the problem is, and will continue to be - customer or user confidence. That is what it is all about. If the paying public refuse or are reluctant to travel on your aeroplane, you're 'dead in the water' so to speak.

    John Green

  15. #45
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    Quote Originally Posted by John Green View Post
    If the paying public refuse or are reluctant to travel on your aeroplane, you're 'dead in the water' so to speak.

    John Green
    I don't think that's likely.
    Several airlines have all (or most) Airbus fleets...and I'd guess there are some route segments where if have to fly Airbus equipment.


    Besides, I think the travelling public (at least in most countries) is sophisticated enough to put issues like this into perspective.
    There are two sides to every story. The truth is usually somewhere between the two.

  16. #46
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    RE Skin wrinkles:

    I've seen many an airliner with similar wrinkles. They are not uncommon.
    Nothing to do with fatigue, just the skin bending and stretching as the fuselage moves, generally on landing.

    Examples:

    Wrinkles to be seen aft of the wing to body fairing on the lower part of the fuselage all the way back to the reg number.
    Clicky

    And this one

    There are many more examples, but A.net is annoying me as it is terribly slow this morning, so thats all you're getting as exmples for now.
    Bmused55

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  17. #47
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    Quote Originally Posted by J Boyle View Post
    Besides, I think the travelling public (at least in most countries) is sophisticated enough to put issues like this into perspective.
    The travelling public want to fly cheap full stop. They don't give a damm about who they fly on or what they fly on. That is the level af most passenger sophistication.

    The cracks in the 380 wing? Due to a good inspection program carried out by good aircaft engineers () The cracks have been found and delt with. NEXT!

    Rgds Cking

  18. #48
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    Cheap? Certainly. Safe? Very certainly.


    John Green

  19. #49
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    If you want to see how much an aircraft can be patched up, you only have to
    look at one of the USAF's KC-135s.

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    Latest from the BBC


  21. #51
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    Quote Originally Posted by ~Alan~ View Post
    If you want to see how much an aircraft can be patched up, you only have to
    look at one of the USAF's KC-135s.
    If I had just spent 200 million Euros on my new "state of the art" 500 seater, I really wouldn't want to be comparing it to a 55 year old military tanker.

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