Investigators say they should know within hours if they can salvage any information from the black boxes of the Egyptair flight that plunged into the Mediterranean Sea last month.
The two data recorders were recovered last week. But investigators said Sunday that both had sustained heavy damage.
Once the repair work is done, it will be determined if the data from the cockpit voice recorder and the flight data recorder can be easily downloaded, sources at the Egypt-led investigative committee said.
According to the sources, experts from France and the US took part in repairing the damage in cooperation with a special unit at the Egyptian Civil Aviation Ministry, which specializes in aviation accidents.
Egyptair flight MS804 was en route from Paris to Cairo on May 19 when it crashed into the Mediterranean, some 290 kilometres north of the Egyptian coast, killing all 66 people on board.
The Airbus A320 veered to the left and then spun around rightwards in the last minutes before it crashed, according to Greek and Egyptian officials. No distress call was received.
Last month, Egyptian Civil Aviation Minister Sherif Fathy said that an extremist attack appeared a more likely cause than mechanical failure.