Boeing has reached a milestone in building the stretched version of the Dreamliner which Air New Zealand will be the first airline in the world to fly.
Progress on the prototype comes as Air New Zealand is about to finalise its cabin configuration for the fuel efficient plane, whose delivery is running years late but still promises to be a "game changer" for the airline.
The first version of the aircraft has been in service for nearly a year and its entry into the market has been seen as relatively smooth, although the National Transportation Safety Board United States safety authorities last week recommended extra scrutiny of those planes fitted with new General Electric engines after mechanical troubles.
Air New Zealand's planes will have Rolls Royce engines.
So far five airlines fly almost 20 of the original 787-8 Dreamliners.
Air New Zealand has ordered 10 of the 787-9 model which are about 6m longer than the first one and capable of carrying up to 40 more passengers and flying almost 700km further.
Boeing assembles the planes at its Seattle manufacturing base and a new facility in South Carolina.
After being plagued by multi-million dollar delays due to outsourcing problems and some development failures, it says it is about to step up its production beyond 3.5 a month in a pre-Christmas surge.
"We are closely monitoring the entire supply chain to ensure operational stability as we systematically ramp up to higher rates," a spokeswoman told the Herald.
"We plan to complete the next production system rate increase by the end of the year, tracking as expected to the planned programme rate of 10 airplanes per month by late 2013."
Within the last few weeks "major assembly" for the first 787-9 began when Japan's Kawasaki Heavy Industries started installing passenger door frames into the forward midbody section of the fuselage.
When finished the section will be flown aboard a transporter to South Carolina where it will be integrated with other sections before being flown to Seattle for final assembly next year.
It will then undergo flight testing for certification and first delivery - to Air New Zealand - is still scheduled for early 2014, more than three years late.
Delays have been a huge source of frustration for the airline but it is confident the plane will be delivered according to the revised timetable.
After the release of its full-year result, chief executive Rob Fyfe said the airline was continuing to get strong encouragement from Boeing that the delivery was on schedule.
"Because it's a variant of type, being a stretch of the  8, the certification process and the risks are certainly far less substantial than with the original aircraft."
Fyfe said the decision by Qantas to defer delivery of 35 of the 9-series planes for two years and refurbish existing aircraft would add to his airline's advantage.
"There's two dimensions to it being a game changer," he said. "We will get a material operating advantage when our aircraft arrive against our competitors flying old aircraft."
Airframe maintenance costs could fall by 30 per cent and fuel costs in the region of 20 per cent.
"When you're only making a two or three per cent margin and fuel's 50 per cent of your costs, that's really valuable," Fyfe said.
The airline was this week tight-lipped on the final cabin interiors but it will be split between business premier, premium economy and economy, including "cuddle class" seating.
Fyfe said it would be consistent with the fitout of its Boeing 777-300.
"It's just a matter of getting the balance right."
The airline this week said it was fully into the design phase for the interior and was working on the fit-out with seat manufacturers and its design company Altitude.
Routes have not been finalised but as the aircraft will initially directly replace Boeing 767s they will be used on routes throughout the Pacific and Japan. The airline will explore new long haul routes, including to South America, and look at using it to add frequency to existing routes.