Smoke was detected in the toilet and the aircraft’s electrics, just minutes before the signal was lost on Thursday, according to data published on air industry website the Aviation Herald on Friday.
The data came through the Aircraft Communications Addressing and Reporting System (ACARS), a data link for sending messages between planes and ground facilities, CNN reported.
A screen grab of data has time stamps that matched the approximate time the aircraft went missing.
It said the system showed that at 2.26 a.m. on Thursday, smoke was detected in the Airbus A320 toilet.
A minute later at 2.27 a.m., there was an avionics smoke alert.
The last ACARS message was at 2.29 a.m., and the contact with the plane was lost four minutes later at 2.33 a.m.
ACARS is used to routinely download flight data to the airline operating the aircraft.
However, the alerts do not necessarily mean a fire occurred on the plane or that the crew even knew about the alerts, which are automatically transmitted, aviation experts cautioned.
Still missing are the flight data and cockpit voice recorders, sometimes called the “black boxes.”
“(The data) doesn’t tell us anything, whether it’s an explosion because of a bomb or because of a mechanical fault, but immediately it narrows down the area that we’re looking at,” aviation analyst Richard Quest said.
“We’re now no longer worried about wings or what else might have happened, or other flight control surfaces.”
The plane carrying 66 people — 56 passengers and 10 crew members — disappeared while flying from Paris to Cairo.
No survivors have been found, but searchers in the Mediterranean Sea located debris on Friday, including suitcases and human remains.
Greek Defence Minister Panos Kammenos relayed the Egyptian discovery of the body part, seats and suitcases, citing Egyptian officials.
Later, the airline issued a statement saying more remains, personal belongings and aircraft seats had been discovered.
The Egyptian military said it had found parts of the aircraft and passenger belongings about 290 km north of the coastal city of Alexandria, Egypt.
European Space Agency satellites spotted an oil slick in the area where the flight had vanished – but the organisation said there was no guarantee it was from the plane.