MIAMI — United’s first Boeing 787-9 rolled off the final assembly line in the late hours of the night on Tuesday. It was quickly taken away to a nearby paint hangar, where it remains concealed.

The airplane remains unpainted aside from the tail, and should appear in about a week fully painted.

United Airlines will be the first North American airline to take delivery and operate the newer and bigger 787-9. The carrier expects to take delivery of its first 787-9 sometime this summer. After it completes its introduction into service procedures, the new Dreamliner will be scheduled on existing 787 routes.

“The 787-9 is an amazing aircraft that builds on the 787-8’s proven fuel efficiency, performance and customer comfort,” said Ron Baur, United’s vice president of fleet. “We are excited to add the 787-9 to our Dreamliner fleet as it gives us even more flexibility and range to capitalize on our extensive worldwide route network.”

In February, United announced that the first 787-9 route would be between Los Angeles and Melbourne, Australia, set to begin on October 26, 2014.

United’s -9 Dreamliners will have 252 seats. There will be 48 seats in BusinessFirst (in a 2-2-2 configuration), 88 Economy Plus seats (United’s extra legroom economy seats), and 116 economy seats (in a 3-3-3 configuration).

According to FAA registration data, the registration is expected to be N38950.

United is not new to the Dreamliner, however. It was the airplane’s North American launch customer for the original version, the 787-8. The airline debuted its the aircraft in August 2012, and began flying passengers on November 4, 2012.

Currently, United operates 10 Boeing 787-8s, and it has an additionally 55 Boeing 787 family aircraft on order.