According to information provided by a source close to Embraer, and reported by 'Caixa-Preta Blog', by aviation journalist Solange Galante, the aircraft was flying at about 20,000 feet when it fell and went down vertically in about a minute, leveling off just over 3,000 feet on a terrain with approximately two thousand feet of altitude and the altimeters on board locked in the maximum. The source said that it was not possible to evaluate the maximum speed reached by the aircraft during that drop, that surpassed −4 G, enough to twist its structure, causing severe damage and making the aircraft unusable for new flights. The source also said some pieces broke from aircraft during the descent.
Fortunately no one was injured, and the aircraft was able to land safely on Embraer Gavião Peixoto airport. The aircraft will undergo evaluations to determine what caused the sudden drop and also the damage caused to aircraft.
According to data recorded on FlightRadar24, the incident with KC-390 occurred within 56 minutes of flight, when a sudden change in altitude and heading can be observed and the subsequent return to Gavião Peixoto after the pilots declare emergency.
Embraer has released an official statement that can be read below:
A prototype of the KC-390 multi-mission transport aircraft performed on Thursday morning, October 12, in-flight tests for stall situations, which result in aircraft altitude loss due to the decrease in lift force as part of the certification testing campaign.
Due to the maneuvers performed and following established protocols, the crew requested an early return to the base, normally landing at the company's aerodrome in Gavião Peixoto (SP) where the test campaign is carried out.
The KC-390 is scheduled to enter service in 2018, according to the schedule of the program. Currently, two KC-390 prototypes total more than 1,300 flight hours.
Source (In Portuguese): http://www.cavok.com.br/blog/incidente- ... tificacao/