The damaged flight data recorder from the EgyptAir plane that crashed last month has been successfully repaired in France.
Egyptian investigators say that work on the Airbus A320’s cockpit voice recorder will begin “within hours”.
It paves the way for experts to analyse data that could help explain what caused the crash.
Flight MS804 from Paris to Cairo plunged into the Mediterranean Sea on 19 May, killing all 66 people on board.
Egypt’s investigation commission said in a statement that the flight data recorder had been successfully repaired by the French accident investigation agency laboratory.
The voice and flight data recorders, known as black boxes, arrived in Paris from Cairo on Monday so that salt deposits could be removed.
They will be sent back to Cairo so the data can be analysed.
Also on Monday, the Paris prosecutor opened a manslaughter investigation into the crash.
A spokeswoman told the Associated Press that it would begin as an accident inquiry because there was no evidence so far to link it to terrorism.
Investigators appear to think the Airbus A320 was not brought down deliberately.
The flight recorders were recovered from the plane’s wreckage, about 290km (180 miles) north of the Egyptian coast and at a depth of about 3,000m (9,800ft).
Automated electronic messages sent by the plane revealed that smoke detectors went off in a toilet and in the avionics area below the cockpit, minutes before the plane’s signal was lost.
Radar data shows the plane turned 90 degrees left and then 360 degrees to the right, dropping from 11,300m (37,000ft) to 4,600m (15,000ft) and then 3,000m (9,800ft) before it disappeared.