LOS ANGELES — Boeing has confirmed that the third variant of the 787, the double-stretch 787-10, will be assembled exclusively in its Charleston, South Carolina facility, making it the first of any Boeing commercial model to be completed away from the U.S. west coast.

The decision was not unexpected since the 110-ft midbody section of the 787-10 airliner will be 10 ft. longer than that of the 787-9, making it marginally too long to be transported in the fleet of specially converted 747-400 Large Cargo Freighters (LCF) which form the backbone of the logistics network transporting parts to the assembly lines in Everett, Wash, and South Carolina.

"We looked at all our options and found the most efficient and effective solution is to build the 787-10 at Boeing South Carolina," says 787 vice president and general manager Larry Loftis.

The 787-10 will be 224 ft. in overall length when assembled compared to 206 ft. for the recently developed 787-9 and the 186 ft. long 787-8. The largest single structural elements carried in the LCF to the final assembly line in Everett are the wings made in Nagoya, Japan, and the midbody. This large fuselage unit is made up from the Alenia-built Sections 44 and 46, the Kawasaki-built Section 43 and 45 main landing gear wheel well, and the center wing box made by Fuji in Japan. The sections are joined together for all 787 versions in Charleston before either being trucked to the adjacent line for local assembly or flown across country to one of two assembly lines currently operating at Everett.

The 787 production line in South Carolina is set to increase production from its current rate of three aircraft per month to five per month in 2016. The 787-10 will be introduced onto the line in 2017 as part of the plan to increase the rate at Charleston to seven per month by 2019-2020. By then Boeing plans to be producing seven 787-8s and 787-9s from Everett on a single line, for a total of 14 aircraft a month between the two sites. Boeing currently operates two 787 assembly lines in Everett, but expects to close down one of them — a temporary surge line — as it perfects a revised production system designed to handle the standard and stretched models. The area occupied by the surge line will then be used to develop the production system for the 777X.

Boeing has so far taken orders for 132 787-10s, representing 13% of the overall 787 firm backlog of 1,043. Launched at the 2013 Paris air show, the first 787-10 is scheduled for delivery in 2018.