Embraer’s KC-390 jet airlifter/tanker flew for the first time in early February, but the company has not yet put its technologically ambitious fly-by-wire flight control system to the test.
For the first flight, the aircraft’s flight-control system was fully operational, but set to direct-law mode, Paulo Gastão Silva, vice-president of the KC-390 programme, tells Flightglobal.
The KC-390’s active control sidesticks also were not fully operational during the 2h flight, he says. Over the course of the first phase of the two-year test campaign, Embraer will gradually enable more complex aspects of the fly-by-wire system.
“During first phase we complete test points needed to freeze the dynamic definition of the aircraft,” Gastão Silva says. “We will cover the initial envelope with direct mode and then start adding the other functions going to higher modes for the system.”
Direct mode is similar to flying a conventional aircraft with a direct link between flight controls and the wing control surfaces. None of the built-in protections of the fly-by-wire controls were enacted.
The KC-390 will eventually be flown in normal mode, where the fly-by-wire controls improve efficiency and provide flight-envelope protections that prevent the aircraft from stalling or performing aggressive manoeuvring.
Direct mode lacks those protections and would not be used by pilots during normal operations.
The KC-390 features a Rockwell Collins Pro Line Fusion cockpit with BAE Systems active side control sticks that emulate the experience of using mechanical flight controls that require the pilot to use appropriate force in response to aerodynamic loads.
“The active control sticks are part of the flight controls, so they were there but we start flying in basic modes and then authorize the function of higher modes progressively,” Gastão Silva says. “For first flight we were not using yet the full capability of the active sticks.”
The first prototype of two that will perform the test campaign will continue flying until the second KC-390 comes online in a few months, Gastão Silva says. The first aircraft also will continue to undergo ground testing to inform future test flights, which is not indicative of any discoveries during its maiden sortie, he says. The second aircraft is in the final stages of structural assembly.
The aircraft’s cargo-handling system was installed but not operational during first flight because there were no plans to use it, he says. The fuel system for the aircraft was installed but not the wing fuel pods and internal tanks that will be used for aerial refueling. That put the aircraft’s empty takeoff weight “in the middle of the envelope”, which was “well within the weight expected from our calculations”, he says.
“Both prototypes will be fully representative of the aircraft’s final configuration,” he says.” We don’t need to wait for the second prototype for envelope opening or to fly specific conditions. We can do it with either one of the prototypes.”