787 centre wing box redesign buckles schedule

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In mid-March, Steven Udvar-Hazy, chairman of International Lease Finance, Boeing's biggest customer, declared to an audience of Wall Street analysts that Boeing would have to redesign its centre wing box, resulting in further delays.

Udvar-Hazy's comments sparked a firestorm of speculation as to the impact of the redesign on the schedule that began to look as though it was slipping once again.

Programme sources have told Flight that the design change was necessitated after Boeing and its structural partners found potential for premature buckling in the structural spars that give the centre wing box its strength.

During the initial development phase of the centre wing box, the structural spars were designed to support the required structural loads. The original design was changed when the weight of the Dreamliner began to increase. The structural spars, which are made of composite, were reduced in width as a weight-saving measure.

787
 © Charles Conklin

Boeing and Fuji Heavy Industries manufactured composite test pieces to demonstrate the structural capabilities of the spars. Findings indicated that the composite spars were buckling prematurely compared with metal spars of the same width. Stiffeners are being affixed to restore structural integrity to the spars on the existing centre wing boxes, which are manufactured by Fuji Heavy Industries in Japan.

Udvar-Hazy's comments came as Boeing had already completed the redesign and was already preparing to incorporate the fix to the existing centre wing boxes on the six test aircraft. "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 20 March statement from Boeing said. "The robust test process in place on the 787 programme has confirmed the majority of our designs, but we have found the need for some improvements. The centre wing box issue has been addressed."

Boeing in April conceded the centre wing box fix and additional travelled work have added two months to the schedule, pushing power-on to June.

In the months that preceded this incident, Boeing had closely guarded the status of the programme until it was ready to release its comprehensive assessment at the end of the first quarter. The transparency and visibility of the early part of the 787 programme had given way to rare public statements about the status of assembly. In a media environment hungry for information about the status of the programme, this story ballooned rapidly.

The centre wing box issue itself was largely resolved when Udvar-Hazy revealed it, although it underscored the publicly perceived gap between official comments about the programme and statements by those aware of the programme's internal issues.

2007

15 January First centre wing box and Section 43 arrive in Charleston, South Carolina from Nagoya, Japan.

23 March Sections 44 and 46 arrive in Charleston from Grottaglie, Italy.

25 April First horizontal stabiliser arrives from Grottaglie.

7 May First vertical stabiliser arrives from Frederickson, Washington.

11 May First nose section and aft fuselage section arrive from Wichita, Kansas and Charleston, South Carolina.

15 May First wings arrive from Nagoya, Japan.

16 May Final assembly gets under way for ZA001 after delivery of the first centre fuselage section from Global Aeronautica.

25 June ZA001 rolls out of the factory to be painted before its official roll-out.

July Structural sections arrive in Everett for static airframe ZY997.

8 July Boeing's first 787 is presented to a crowd of 15,000 for its official roll-out.

August Boeing changes delivery schedule to hold 787 structures at partner sites to reduce travelled work.

5 September Boeing pushes first flight from late summer 2008 to mid-November/mid-December. First deliveries unchanged.

10 October First flight delayed to end of the first quarter. First delivery to ANA by November or December 2008.

16 October Mike Bair replaced as 787 programme manager by Pat Shanahan.

November Structural sections arrive in Everett for fatigue airframe ZY998.

11 December Boeing maintains 109 787s will be delivered by the close of 2009.

2008

16 January First flight delayed to end of the second quarter. First delivery to ANA set for early 2009.

February Structural sections arrive for Dreamliner Two (ZA002).

28 March Boeing acquires 50% of Global Aeronautica.

9 April Additional delays - first flight to the fourth quarter of 2008 and first delivery to the third quarter of 2009. The 787-9 is pushed to 2012, 787-3 service entry is uncertain, and 25 787s are set for delivery by the end of 2009.

April Structural sections arrive for Dreamliner Three (ZA003).

25 April Boeing moves the static airframe ZY997 out for testing.