Embraer’s first KC-390 flight test aircraft ran off the runway during a ground test in Gaviao Peixoto, Brazil, on 5 May, the company says.
The crew of the aircraft exited the aircraft without injury, the company adds.
Embraer has started an investigation to understand what led to the runway excursion. The company also reported the incident to CENIPA, the aircraft accidents investigation and prevention bureau of the Brazilian air force.
Gaviao Peixoto is Embraer's military aircraft production and flight test centre deep in the interior of Sao Paulo state. The airport boasts the longest, publicly accessible runway in the Americas, measuring 4,970m (16,300ft).
The extent of any damage to the KC-390 was not immediately available.
The prototype, registration PT-ZNF, returned to flight two months ago after fixing damage caused by a dangerous incident in flight test on 12 October. In that incident, the crew recovered the aircraft after losing control during a slow-speed stall test.
Embraer showcased the same aircraft last month at the FIDAE air show in Santiago, Chile, flying a group of international journalists over the Andes to demonstrate the aircraft’s fitness to continue participating in the military certification programme.
Embraer plans to deliver the first KC-390 to the Brazilian air force’s 11th Wing in Rio de Janeiro by the end of the year.