SEATTLE – The Boeing Co.’s 787 Dreamliner will be flying over the Puget Sound this weekend.

At least, pieces of it will be.

Friday morning, Boeing’s Large Cargo Freighter arrived in Seattle with its first load of 787 components, marking a significant step in the new plane’s program.

The modified freighter will spend a few days here conducting test flights before delivering its cargo to the next stop on its worldwide manufacturing line: South Carolina.

“Today is an exciting day for Boeing and our Japanese partners,” said Scott Strode, 787 vice president of airplane development and production, in a prepared statement. “Transporting these parts … is the first step in assembling the first 787. We’re very pleased with how it went and with the quality of the parts received.”

Boeing will use three modified 747-400 freighters to carry Dreamliner parts between partner sites in Japan, Italy, South Carolina and Everett. The company recently rolled out its second customized cargo plane, dubbed the Dreamlifter. The freighter is the first of the three-plane fleet to sport the new white-and-blue livery. The modified cargo plane flying around Seattle hasn’t been painted yet.

At Centrair Airport in Nagoya, Japan, crews loaded Boeing’s freighter with section 43, a segment of the forward fuselage, and the center wheel well and center wing tank. Kawasaki Heavy Industries made the fuselage section. And Fuji Heavy Industries joined together the center wheel well and wing tank, which were built by Kawasaki and Fuji.

The entire process took less time than Boeing had anticipated, said Mary Hanson, spokeswoman for the Dreamlifter program.

“I’m told it went very well,” Hanson said.

As part of its requirements for U.S. Federal Aviation Administration flight certification, Boeing will perform a series of test flights with the cargo-laden Dreamlifter this weekend. The freighter should arrive in Charleston, S.C., early next week, Hanson said.

In South Carolina, Vought Aircraft Industries and Global Aeronautica will complete several steps of Dreamliner production: fabricating two aft fuselage segments; connecting fuselage sections built in Japan, Italy and South Carolina; starting stuffing the wiring; and applying the initial coats of paint.

If everything remains on schedule, Dreamliner parts will arrive in Everett for final assembly this spring.