A version of this article appears in the April 21 edition of Aviation Week & Space Technology.

Embraer will begin final assembly of the first KC-390 multirole tanker transport at the end of April, marking a major milestone in the Brazilian company’s ambitious plans to diversify into the military airlifter market.

The fuselage, empennage and wing sections of the first aircraft are being completed prior to assembly at a specially built production site at Gaviao Peixoto, Embraer’s extensive test facility near Araraquara in south-central Brazil. The final body join, expected to take around three weeks, starts the clock ticking on a fast-paced development-and-test program, which is set to begin with first flight at the end of this year and culminate in entry into service with the Brazilian air force (Forca Aerea Brasileira-FAB) in 2016.

The twin turbofan-powered airlifter was launched in 2009 when the Brazilian government signed a development contract with Embraer. “Negotiations are ongoing” to convert a letter of intent from the FAB for 28 aircraft into a firm production contract, says Fernando Fialho, KC-390 program strategy manager. The company, which is building the initial two KC-390 prototypes under a firm contract, expects negotiations to be completed in coming months. In addition, Embraer holds letters of intent for a further 32 aircraft from Argentina, Chile, Colombia, the Czech Republic and Portugal.

Based on FAB requirements for a replacement for its fleet of 22 C-130Hs, the 115.5-ft.-long KC-390 has emerged as a key competitor to Lockheed Martin’s C-130J. Embraer believes its fly-by-wire, turbofan-powered KC-390 could take a 15-20% portion of the C-130 replacement market, which it estimates as 728 aircraft in 77 countries. Designed with faster transit speeds in mind, the International Aero Engines (IAE) V2500-E5-powered aircraft will be able to make short-field takeoffs and landings from austere strips and yet have an airliner-like cruise speed of 465 kt. (Mach 0.8) at an operational ceiling of 36,000 ft. The maximum payload will be 57,320 lb. (26 tons), although design range with a distributed load of 50,700 lb. is 1,200 nm.

After a series of design evolutions the final configuration was confirmed following a critical design review in 2013. The KC-390’s cargo compartment is 41.6 ft. long, 11.3 ft. wide and varies in height from 10.5 ft. in the aft ramp area to 9.7 ft. in the forward fuselage. An integrated cargo-handling system is designed for loading vehicles or, alternately, up to seven 88-in.-wide 463L-standard military air cargo pallets or, in a mixed configuration, 36 troops or 30 paratroopers and six 463L pallets loaded lengthwise. Up to 80 regular troops can be transported in airlift operations. The ramp is 19 ft. long, 11.3 ft. wide, and total useful volume of the cargo compartment is 5,968 cu ft.

Unlike the traditional assembly of previous Embraer aircraft, which begins with integration of the wing box and center fuselage, the KC-390 fuselage will be put together before the high-mounted wing is added. Czech manufacturer Aero Vodochody delivered the last major component, the rear fuselage, directly to Embraer in March, along with other elements including doors, hatches, the cargo ramp and fixed leading edge. The aft fuselage section, at 21.3 X 14.7 X 10.8 ft., was the largest single aerostructure ever made in the Czech Republic, according to Aero.

Other key structural partners include Argentina’s Fabrica Argentina de Aviones, which is responsible for the cargo ramp door, tail cone and spoilers; Portugal Engineering Manufacturing (OGMA), which provides fuselage panels, fairings and doors; St. Louis-based LMI Aerospace, supplier of leading-edge slats. Spain’s Aernnova, a longtime Embraer supplier with a plant in Sao Jose, is responsible for the composite flaps, ailerons and rudder.

An iron bird test rig for the KC-390 is also under assembly at Embraer’s Eugenio de Melo engineering facility in Sao Jose dos Campos. The rig will be used to validate avionics and flight controls, as well as electric and hydraulic systems. Close by in the same facility an engineering mockup of the cockpit and forward fuselage section has been assembled to help define the layout of the Rockwell Collins Pro Line Fusion flight-deck and mission-systems avionics, twin Elbit head-up displays and active side-stick controllers developed by BAE Systems.