The CBS News report
EgyptAir Flight 804: Black boxes for crashed airplane located, Egypt government sources claim - CBS News
seems to have lost something in translation.
The black boxes being "located" would mean they detected the pingers, though this is not explained.
CBS News also reports that the ACARS reports indicate "smoke was coming from one of the engines."
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A NY Times 'expert' focuses on loss of the autoflight control computer while flying near maximum speed and altitude, and then the loss of the spoiler elevator controller.