"The aircraft is undergoing scheduled tests," Borisov told reporters.
He added that Komsomolsk-on-Amur aircraft manufacturing plant would continue to supply prototypes of the aircraft for testing.
"Three new aircraft, which the company will deliver in 2017, will join the first stage of the testing program," the official pointed out.
The T-50 is designed by the Russian Sukhoi aircraft manufacturer as part of the PAK FA, a fifth-generation fighter program of the Russian Aerospace Forces. It is a single-seat, twin-engine multirole fighter jet designed for air superiority and attack roles and equipped with advanced avionics system and an active phased array airborne radar. The first flight of the aircraft took place in 2010.