B787 Wing Box Redesign

[1 to go]

The Financial Times reports that the wing box on the B787 will need to be redesigned and mentions another 6 months delay.

[Dysag]

Steve Hazy of ILFC always knows before the airlines.

http://blog.seattlepi.nwsource.com/aerospace/archives/134610.asp

[llondel]

Surely once the aircraft is delivered, the wings will be unpacked from the box? :}

Better they take another six months and get it right than ignore a problem and repeat the DC10 example (rear cargo door) where a known design fault was not fixed despite being known about during development and highlighted by the American Airlines incident. Perhaps the A380 design process wasn't so bad after all with its delays...

[Enderby-Browne]

Why do so many people believe everything they read in the papers?

Does anyone really think the FT's aerospace guy is objective? Be a first if he were...

For "redesigning" one could read "considering changing", but that hardly sells newspapers, does it?

And like the FT's "Jeez, I'm important" correspondent, Udvar-Hazy's way too fond of himself. I don't much like the way he and a couple of airline bosses/governments are calling the shots so much these days.

[World of Tweed]

The root cause for these delays is more likely influenced by overly ambitious time-tables, a new manufacturing process and the use of technology and materials once restricted to smaller scale projects.

In short neither Airbus or Boeing have allowed a sensible amount of time for the development of their aircraft - both step changes in current technologies/products.

Boeing didn't move its HQ from seattle to Chicago for nothing... I suspect it was very much along the lines of getting the engineers out of the board room and this is the result.

[Putt]

Caution for Dysag, the Seattle PI traditionally wallows in pink journalism. They especially enjoy running down Boeing and deal in rumor and innuendo.
Udvar-Hazy has always been outspoken, rightly or wrongly, he is the customer.
Boeing relied on Supplier Partners, didn't work, in some cases. Some Tier 1's failed to "manage" their subs.
Obviously, new technology and new innovations, coupled with an ambitious schedule...(sound of trumpets) and you have schedule creep.
This will not detract from another fine Boeing product taking to the skies.
And no, I don't work for Boeing.:cool:
putt

[flatfootsam]

Seattle PI might might have an agenda, however Flight Internationals' Flightblogger article below is particularly revealing -

Boeing engineers previously changed the centre wing box design to save weight by thinning out the density of the spars.
However, Flightblogger reports, that move backfired after the company learned the redesign could trigger premature buckling of the load-bearing spars.
Asked for comment, Boeing did not deny the decision to redesign the centre wing box.


- What!? a center wing box primary structure that can't carry compression loads up to ultimate load. that's a howler of major proportions for any designer, but then if you lift the technology from a military program (v22), you're bound to have problems...maybe they're preoccupied with the tanker deal.



Blaming the sub contractors doesn't work either, as they're risk sharing partners, but Boeing has the design authority (and it's one of their intellectual property rights)

And from Leeham news and comment (not always reliable):
Boeing has confirmed there are wiring redesigns occurring - That's just comical.

Scuttlebutt is is 787 n°1 is a going to be used as an expensive ornament parked up out of sight and embarrassments way, n°'s 2 & 3, for the structure certification testing and the first pre- production example getting off the ground will be n°4...then there's the 1000's of hours of certification testing to complete.

Udvar-Hazy has alluded to problems upstream that the disingenuous mutterings from boeing don't cover

[old,not bold]

For those who are interested...

From ATW;

Boeing redesigns 787 center wing box, no further delay confirmed
Friday March 21, 2008
Boeing admitted yesterday that it has "found the need for some improvements" on the 787, specifically in the center wing box, and that the fixes are underway for those aircraft undergoing assembly.
The company did not confirm whether the extra work would result in another delay. "It is a normal part of the development of a new airplane to discover need for improvements, and that is what we are experiencing on the 787," a Boeing spokesperson said in an e-mailed statement.
"Boeing is working its normal processes for developing a new airplane. The test process is working when issues are discovered and we are reacting appropriately by implementing normal design validation and fixes when we find issues," the statement continued, adding that "the center wing box issue has been addressed." The manufacturer said the fix is being installed on six 787s at its Everett factory, four of which are in final assembly. The solution will be incorporated from the start for the seventh aircraft and beyond.
The statement followed a story in the Financial Times in which a Boeing spokesperson acknowledged "some redesign work" in the wake of comments from ILFC Chairman and CEO Steven Udvar-Hazy at this week's JPMorgan Transportation and Aviation Conference in New York. The leader of the world's largest aircraft lessor said the state of the 787 program was "not pretty" and that he anticipated a further six-month delay as a result of problems with the center wing box, which were unidentified. The Boeing spokesperson told FT that "things are more complex than what [Udvar-Hazy] said."
Boeing is expected to update the 787's progress and announce a delay, if any, in late March/early April. Two weeks ago, Goldman Sachs issued a client note indicating that some sources believed a further three-month delay would push first delivery back to the 2009 third quarter
ATW

[Towerman]

and to add to the win box issue, heard yesterday that there is a further issue with the 787 Titanium Bolts reacting with the composite material used and causing corrosion - anyone else heard this??:confused:

[DrKev]

and to add to the win box issue, heard yesterday that there is a further issue with the 787 Titanium Bolts reacting with the composite material used and causing corrosion - anyone else heard this??

I'm no expert on metals chemistry but with titanium's corrosion resistance and general difficulty to get it to react with anything if not heated, I doubt it very much. In fact I'd even go so far as to give a tentative "I think that's bollox" to that rumour.

[graham2400]

DrKev,

I'm pretty sure I read in the "Skunk Works" that titanium (depending on the exact alloy) can be VERY susceptible to problems when mated with incompatible materials. e.g bolt heads dropping off when tightened up using cadmium plated tools.

Maybe not 'B@ll@x' after all !

Regards,

Graham

[SpatialDSim]

Ok, here goes, first post. I don't think the typical environment in wing structures will be conducive to corrosion of Titanium. A good site is found http://www.key-to-metals.com/Article24.htm

The design/build process of any large or complex item using new(er) techniques or technologies is bound to produce delays. The choice of a company to either

A. Include a "sufficient" fudge-factor in the quote to account for the majority of these delays. Downside to the customer is at the time of order, so perhaps the company doesn't get the original order.

or

B. Schedule without those delays and push the delivery date as necessary is a marketing decision. Downside here is after order and only damages your future reputation for delivery on-time.

[Brian Abraham]

Titanium is a metal that does have it's own problems according to books on the SR-71 developement. Over ageing causes brittleness and a sample will shatter when dropped from desk height. The metal is incompatable with cadmium, chlorine or flourine. A line drawn on it with a Pentel pen will eat a hole through the metal in 12 hours. As hinted at in graham2400's post on the production line they had problems with bolt heads coming off which was caused by cadmium deposits left on the bolt heads by cadmium plated spanners. Got rid of the cadmium plated spanners and all fixed. As graham and Towerman suggest, perhaps an old lesson beind relearnt, or interreaction with the composite.

[yowie]

Isnt a resin based composite chemically inert when fully cured? Interesting if not!

[mary_hinge]

I’ve heard mutterings of “potential” Hydrogen Embrittlement problems with certain fasteners, but that was some months back and the problem had been resolved. (as A380 suggests)

As the saying goes, a rumour will go twice around the World whilst the facts are still getting their boots on:ok:

[BEagle]

"It is a normal part of the development of a new airplane to discover need for improvements, and that is what we are experiencing on the 787"


Masterly spin. Quite masterly.

Whilst the odd flap tweak or a vortex generator here or there might be considered such an 'improvement', total design of the 7-late-7's centre wing box structure is in an entirely different league.

Still, I suppose it diverts attention from 777 fuel systems and the loss of the KC-X contract.....

[ARINC]

and to add to the win box issue, heard yesterday that there is a further issue with the 787 Titanium Bolts reacting with the composite material used and causing corrosion - anyone else heard this??

All fixings on A380 composite frames are made with Titanium bolts....:ok:

[Bus429]

Suspect commercial (sales) departments at Airbus and Boeing make delivery promises without consulting the technical people. (Strange, just like the aircraft maintenance industry:ok:)

[SpatialDSim]

Whilst the odd flap tweak or a vortex generator here or there might be considered such an 'improvement', total design of the 7-late-7's centre wing box structure is in an entirely different league.


I don't think it's possible to do a "minor change" to the load-bearing box. If you change just one little thing, you've got to go back and do the FEA (Finite Element Analysis) again. So even if they just missed a single hole for the bolt for the clip to hold the strap that holds the name-tag on, it's a "major".

But, on the other hand, believe nothing of the press releases and the reason for the delay. They forgot the landing gear.

Re the Titanium bolts, if everyone is using them, I'd bet the kinks have been worked out. I don't recall seeing any "cadmium-plated" sockets in my A&P's toolbox. They are mostly Chrome plated from Craftsman or Proto. Did a quick google though, and you're right, between '42 and '45 the US military did produce a set of cad-plated (http://alloy-artifacts.com/plomb-gallery-p3.html)aircraft tools at Wright-Pat. It might be more prevalent than I'm aware though.

[Brian Abraham]

A380focal - re the Pentel pen, it was on the production line and not the flight line, so temperature was not a factor. Re hydrogen embrittlement - that was thought to be the problem induced by the heat treatment process, but neither Lockheed or the supplier, Titanium Metals Corporation, were able to prove that was the case. It was eventually resolved by Lockheed replacing its acid pickling facility with one identical to that used by Titanium Metals Corp. The pickling ensured that the item was perfectly clean and prepared before use. So says a book. :8

[Grunf]

Redesign comes in due to the excessive weight reduction exercise conducted on the wing box.

One can ask, in light of the test results for the fuselage (withstand 200% of the limit load - requirement is 150% i.e. the ultimate load, not to go into regulatory lingo for this) one can assume initial design beefed up the fuse (Boeing was not initially sure how the concept will work due to the tooling (mandrel) issues etc).

So, one needs to find a place to do the weight reduction and consequently one hits the wing box. Execution was expected form a bunch of eager, young, stress engineers running Excel spreadsheets and "proving" everything is fine. Now, the correction comes in.

Still, this is not a big problem. Let us all seat and wait for the flight tests to start rolling to see that everything is working fine.

THEN we can start commenting. Up to that point all is "bolloks". So far manufacturing issues are a no-stopper.

One thing we, the engineering community, forget is the fact that lazy B is not obliged to pay the smaller guys (Tiers 2 and down) until the flight tests are completed. They start being short on cash (for obvious reasons!) and they desperately need money to run the operation. However due to unforeseen reasons, not related to this project (crap in financial industry) banks hold short on them not letting them borrow that easily. Therefore the small guy is late so everybody's late.

Please use this in your equation.

Cheers

Cheers

[altonacrude]

Suspect commercial (sales) departments at Airbus and Boeing make delivery promises without consulting the technical people.


It happens in all the tech industries. I saw it for years in information technology. Salesman's pitch to the customer, "What you want is ambitious but achievable. We can help you to do that."

Salesman's pitch to the techos on returning to base, "Hey guys, drinks are on me, I've got a huge order. And Guess What I Sold."

:ugh::ugh::ugh:

[RogerTangoFoxtrotIndigo]

Whats up with the gear? I've heard it said that it doesnt fit but I find that hard to believe.

The wingbox issue has to be serious, how can the redesign of a primary load bearing structure due to risk of failure not be serious? This explains why they have not even began static fatigue testing on the 787.

There is also talk of wings being removed from LN1/2 and reworked to change electrical runs but this may also be due to wingbox structural changes. When you start redesigning on the fly all kinds of knock ons can happen which have to be implimented in the field.

The redesign will also add weight to an aircraft rumoured to be 3000kg (787-8) and 6000kg (787-9) overweight, these are figures from ILFC's Steven Udvar-Hazy who brought the wingbox issue out into the open, you have to start to wonder about performance guarentees.

Added to the uknown unknowns that could be thown up once its powered on and the 787 project has to be of risk of an A380 type stop order so that they can go back to their CATIA and work things through.

Boeing are not telling the truth as evidenced by the statement that wingbox changes are BAU for plane production, I find it surprising is that no aviation journalist has questioned that statement.

As for the titaniunm bolts, can you imaging the chaos if some cadmium plated tools were discovered on the FAL.

[keesje]

This doesn´t sound good.

If this is a real problem large parts of the proto´s will need to be rebuild.

6 months would be optimistic I guess.

:sad:

[barit1]

The story is told - probably true - of a project engineer (a Collier Trophy (http://en.wikipedia.org/wiki/Collier_Trophy)recipient) who told his staff "If your hardware works the first time, it's probably overweight - better to have it break, then add weight only where necessary!" :D