The first KC-390 prototype, PT-ZNF (msn 390001), flew on February 3, 2015.

Final assembly of the KC-390 is undertaken at Gaviao Peixoto in a new facility opened in 2014, which coincided with Embraer and the Forca Aerea Brasilera signing the first acquisition contract.

The second KC-390 prototype PT-ZNJ joined was recently used for paratrooper and cargo dropping trials in conjunction with the Forca Aerea Brasileira and the Exercito Brasileiro.
More than a month was spent at the Forca Aerea Brasilera base at Campo Grande in 2016 undertaking the first air drop assessments, which included container delivery system drops.

Two IAE V2500-E5 turbofan engines, each rated at 31,330 lb (139.4kN) thrust, power the KC-390.

The two prototype KC390s are fully equipped with test instrumentation and each aircraft can perform any flight test role.

KC-390 PT-ZNJ has already conducted initial paratrooper dropping tests including free fall and static line jumps from both the side doors and the cargo ramp. The test period also involved container delivery system and airdrop trials.
The KC-390 is designed to carry up to 66 paratroopers.

The cargo bay is 12.7m (47ft 8in) long, or 18.5m (60ft 8in) including the ramp, and 3.45m (11 ft 4in) wide.

The flight control system is fully fly-by-wire with active sidestick controllers. Avionics include the Rockwell Collins Pro Line Fusion system and a Selex Gabbiano T-20 tactical radar.