Go Back  PPRuNe Forums > Flight Deck Forums > Tech Log
Reload this Page >

B787 Wing Box Redesign

Tech Log The very best in practical technical discussion on the web

B787 Wing Box Redesign

Old 20th Mar 2008, 16:36
  #1 (permalink)  
Thread Starter
 
Join Date: Apr 2002
Location: West sussex
Posts: 44
B787 Wing Box Redesign

The Financial Times reports that the wing box on the B787 will need to be redesigned and mentions another 6 months delay.
1 to go is offline  
Old 20th Mar 2008, 17:28
  #2 (permalink)  
 
Join Date: Jan 2008
Location: southwest
Age: 74
Posts: 287
It looks to be pretty much confirmed...

Steve Hazy of ILFC always knows before the airlines.

http://blog.seattlepi.nwsource.com/a...ves/134610.asp
Dysag is offline  
Old 20th Mar 2008, 17:34
  #3 (permalink)  
 
Join Date: Jan 2007
Location: San Jose
Posts: 726
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...
llondel is offline  
Old 20th Mar 2008, 18:48
  #4 (permalink)  
 
Join Date: Jan 2008
Location: France
Posts: 28
So what does Boeing say? Patience before speculation.

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.
Enderby-Browne is offline  
Old 20th Mar 2008, 19:01
  #5 (permalink)  
 
Join Date: Oct 2002
Location: Northport, NW England
Age: 40
Posts: 339
......Too tight a schedule.

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.
World of Tweed is offline  
Old 20th Mar 2008, 22:11
  #6 (permalink)  
 
Join Date: May 2007
Location: Florence,AZ
Age: 77
Posts: 15
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.
putt
Putt is offline  
Old 21st Mar 2008, 06:47
  #7 (permalink)  
 
Join Date: Oct 2007
Location: East of Java
Age: 60
Posts: 45
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
flatfootsam is offline  
Old 21st Mar 2008, 17:08
  #8 (permalink)  
 
Join Date: Apr 2006
Location: uk
Posts: 820
B787 Wing Box Redesign

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
old,not bold is offline  
Old 21st Mar 2008, 17:44
  #9 (permalink)  
 
Join Date: Jan 2004
Location: Surrey
Posts: 129
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??
Towerman is offline  
Old 21st Mar 2008, 19:38
  #10 (permalink)  
 
Join Date: Nov 2005
Location: A Paddy in Paris
Posts: 108
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.
DrKev is offline  
Old 21st Mar 2008, 21:45
  #11 (permalink)  
 
Join Date: Jul 2007
Location: Warrington
Posts: 2
Titanium - incompatible with certain materials

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 '[email protected]@x' after all !

Regards,

Graham
graham2400 is offline  
Old 21st Mar 2008, 22:18
  #12 (permalink)  
 
Join Date: Mar 2008
Location: Asia
Posts: 4
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.
SpatialDSim is offline  
Old 22nd Mar 2008, 00:45
  #13 (permalink)  
 
Join Date: Aug 2003
Location: Sale, Australia
Age: 76
Posts: 3,829
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.
Brian Abraham is offline  
Old 22nd Mar 2008, 11:39
  #14 (permalink)  
 
Join Date: Feb 2001
Location: Oz
Posts: 250
Isnt a resin based composite chemically inert when fully cured? Interesting if not!
yowie is offline  
Old 22nd Mar 2008, 11:57
  #15 (permalink)  
 
Join Date: Jul 2004
Location: Under a Log
Posts: 264
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

Last edited by mary_hinge; 22nd Mar 2008 at 12:12.
mary_hinge is offline  
Old 22nd Mar 2008, 13:16
  #16 (permalink)  
 
Join Date: May 1999
Location: Quite near 'An aerodrome somewhere in England'
Posts: 25,615
"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.....
BEagle is online now  
Old 22nd Mar 2008, 17:12
  #17 (permalink)  
 
Join Date: Aug 2005
Location: Not Ardua enough
Posts: 266
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....
ARINC is offline  
Old 22nd Mar 2008, 18:25
  #18 (permalink)  

Pilots' Pal
 
Join Date: Nov 1998
Location: USA
Age: 59
Posts: 1,157
Suspect commercial (sales) departments at Airbus and Boeing make delivery promises without consulting the technical people. (Strange, just like the aircraft maintenance industry)
Bus429 is offline  
Old 22nd Mar 2008, 23:17
  #19 (permalink)  
 
Join Date: Mar 2008
Location: Asia
Posts: 4
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 aircraft tools at Wright-Pat. It might be more prevalent than I'm aware though.
SpatialDSim is offline  
Old 23rd Mar 2008, 00:25
  #20 (permalink)  
 
Join Date: Aug 2003
Location: Sale, Australia
Age: 76
Posts: 3,829
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.
Brian Abraham is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.