Boeing admits defect in some 787s

It's been an up-and-down ride for the Dreamliner aft-body manufacturing operation in North Charleston.

The first plane-making factory completed next to Charleston International Airport hadn't been producing Boeing 787 sections for much more than two years when Boeing bought it from Vought Aircraft Industries as part of a broader effort to rein in the jet program's infamous supply chain problems. But in the past few months, Boeing's top executives have praised the facility and its neighbors, saying they've demonstrated they can perform faster than the overall program rate.

That didn't last long: Building 88-19 is back in trouble. Just how much is not yet completely clear.

Over the weekend, in response to questions from an aviation industry blogger, Boeing admitted "incorrect shimming was performed on support structure on the aft fuselage of some 787s." In other words, workers in North Charleston did not properly join the back sections of several Dreamliners that have since been delivered to airline customers or are scheduled for delivery this year.

In a statement, Boeing insisted the issue is "well defined," that it presents "no short-term safety concern," and that the company's engineers are "making progress on a repair plan."

But for the airplane program that has been delayed as it has been hyped and for its particularly embattled local unit, the news of yet another manufacturing defect was certainly unwelcome.

A local Boeing spokeswoman referred questions about the shimming issue to the company's center of operations in Washington.

Speaking in Seattle on Monday, Boeing Commercial Airplanes CEO Jim Albaugh said he doesn't expect the problem to change the 2012 delivery forecast but conceded the review and repair process would have an effect.

"It'll slow things down initially, though," Albaugh said, according to Bloomberg.

Boeing's stock was down 88 cents, or 1.15 percent, Monday, and was falling further in after-hours trading.

Some analysts didn't seem very concerned, however.

"The issue is on the way to being solved," Howard Rubel, who covers Boeing for Jefferies & Co. in New York, wrote in an email. "Boeing caught the flawed process in its reviews and has developed a solution that should not create a delivery delay, as best as we can tell."

Boeing would not say how many Dreamliners, only five of which have been delivered, are affected.

"We have not inspected all 787s, and we've only found it on some," said Lori Gunter, a company spokeswoman in Washington. "We're continuing to work through the issue."

Gunter said the situation is "evolving real time" but that it's unlikely any planes or sections would have to return to North Charleston for fixes.

"The repairs are very straightforward, using standard work processes, so we don't see the need to return the planes anywhere," she said.

Shims are little slivers that fill gaps when larger pieces don't fit evenly together. They prevent the kind of internal movement that can be dangerous on an airplane that flies at high altitudes for decades.

Shimming is part of the standard manufacturing process, but if done improperly, one of the possible consequences is delamination, or the separation of the layers of the plane's skin.

While published reports said the shimming problem had led to delamination on assembled Dreamliners, Gunter would not confirm delamination had already occurred.

The Dreamliner's lightweight composite skin is pasted on in layers and then heated to a hardened shell in facilities, such as Building 88-19.

Bad shimming toward the back of the plane was a problem in 2010, too, and required the teardown and reinstallation of Italian-made horizontal stabilizers, according to Flightglobal, the blog which first reported the most recent issue Saturday night.

Reach Brendan Kearney at 937-5906 and follow him at twitter.com/kearney_brendan.