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B787 Wing Box Redesign

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B787 Wing Box Redesign

Old 23rd Mar 2008, 01:57
  #21 (permalink)  
 
Join Date: Aug 2005
Location: SEA (or better PAE)
Posts: 213
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

Last edited by Grunf; 23rd Mar 2008 at 19:11.
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Old 23rd Mar 2008, 10:57
  #22 (permalink)  
 
Join Date: Nov 2007
Location: Australia
Posts: 29
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."

altonacrude is offline  
Old 23rd Mar 2008, 20:56
  #23 (permalink)  
 
Join Date: Nov 2000
Location: wales (new south)
Posts: 80
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.

Last edited by RogerTangoFoxtrotIndigo; 24th Mar 2008 at 03:44.
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Old 24th Mar 2008, 00:20
  #24 (permalink)  
 
Join Date: Oct 2007
Location: netherlands
Age: 52
Posts: 730
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.

keesje is offline  
Old 26th Mar 2008, 12:33
  #25 (permalink)  
 
Join Date: Feb 2005
Location: flyover country USA
Age: 78
Posts: 4,579
The story is told - probably true - of a project engineer (a 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!"
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