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Engineers on the project say wing design flaw will prevent test flight in 2009

Boeing's 787 “Dreamliner” has been more of a nightmare for many at Boeing as the project has cost significantly more than expected and is still two-years late (and counting).

Another problem in the 787's design has been found, this time in the wings. During tests to certify the aircraft, damage to the wings and wing box of the 787 was found. The damage was delamination of the composite sheets covering the wings under stress.

The Seattle Times reports that the structural flaw in the Dreamliner was discovered in May during ground tests that bent the wings upwards to simulate stress during flight. The stress at the end of rods used to stiffen the upper wing skin panels caused the composite plastic material used in the wings to delaminate.

The damage to the wing occurred just beyond the Dreamliner's load limit, described as the maximum weight the wing is expected to bear in service. The Seattle Times mistakenly reported last week that the damage occurred just over the wing's ultimate load, which is 50% higher than the in-service limit load the wing is expected to endure. The limit load is the FAA test target and proves that the problem with the design of the wing is worse than originally believed.

The plane could have flown after the wing damage, but the test flights would reportedly have been severely restricted. The damage the wing sustained is reportedly not severe enough to have caused any sort of catastrophic failure had it happened in flight.

The design flaw and time needed to devise and implement repairs on the fleet means that the test flight will not likely happen this year according to one engineer on the project. The test flight was delayed in late 2008 to Q2 2009.

The damage to the wings extends inside the fuselage of the aircraft as well making repairs more difficult. The failure in the wing and the wing box is not the fault of Fuji Heavy Industries, who manufactures the components for Boeing. That means Boeing is solely responsible for any cost overruns and time delays because of the issue.

The fix has yet to be certified but could involve engineers creating a U-shape cutout in the end of the upper wing skin stringer and then refastening the reshaped stringer ends with new titanium fittings.



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RE: Confused...?
By cochy on 7/31/2009 4:44:44 PM , Rating: 1
Umm ya cause the A380 is on-time and on-budget.


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