Embraer remains on schedule to complete the joint definition phase and freeze the design of its KC-390 transport in mid-2012, company executives said on 8 August.
The Brazilian manufacturer had previously frozen the configuration of the KC-390, but certain decisions on key design details must still be worked out with major suppliers over the next year, said Orlando Neto, vice president of sales for Embraer Defense and Security.
Embraer does not anticipate major design changes during the year-long process.
The first KC-390 prototype is scheduled to complete its debut flight within three years, in 2014.
The KC-390 supply chain became fixed in late July, with the selection of US-based International Aero Engines to provide its V2500-E5 turbofans.
Embraer also confirmed the KC-390 will join the ranks of so-called "more electric" aircraft, with conventional hydraulics replaced by a full authority digital fly-by-wire control system made by BAE Systems, and electro-hydrostatic actuators supplied by US firm Goodrich.
That completes a supply chain that heavily leverages commercial technology, including Rockwell Collins ProLine Fusion avionics.
Brazil's air force launched the programme in April 2009, then in July 2010 committed to buy 28 of the twin-jet tanker/transports.
Embraer also received commitments to buy 32 more KC-390s from five more countries: Argentina, Chile, Colombia, the Czech Republic and Portugal.
The company does not intend to add new orders for the KC-390 during the joint definition phase. When the aircraft design is fixed after mid-2012, additional customers will be pursued in 2013, Neto added.
Next year, Embraer will start building a final assembly hangar at its military aircraft production centre in Gaviao Peixoto, Brazil.
The KC-390 is being designed to carry a 23 tonne cargo load.
It is aimed initially at replacing turboprop-powered Lockheed Martin C-130s. In the long-term, however, Embraer also projects a need for a commercial freighter variant to launch after 2018.
The stretched commercial version, which retains the same wings and engines of the military variant, could attract as many as 250 orders over a 10-year period, Embraer said.