The 787-10 is the third Dreamliner model. It seats 330 passengers in a typical two-class lay-out, compared with 290 in the 787-9, plus 15 per cent more cargo.
The 787-10 will be produced in Charleston only, because the fuselage is too long to transport it to Everett by air in the special 747 Dreamlifter transport aircraft.
Deliveries will begin in the first half of 2018. So far, Boeing has sold 149 787-10s out of a total of 1,207 firm Dreamliner orders.