I know it might go against the grain here but from:
EgyptAir flight MS804: smoke detected in 'multiple locations' before crash | World news | The Guardian
Shaker Kelada, the former head of Egypt’s plane crash investigations unit, cautioned against reading too much into the data. “Alone, it means nothing. It’s the last four seconds at the end of the transmission. If it’s an indication of anything it could be a followup to an explosion. It could also happen if someone smokes in the cockpit or the bathroom. But there was no warning in the cockpit.
“This could be the first indication of a bomb. Or it can be unrelated. Since we don’t have any further information we cannot tell anything.”
Similar has been said by the BEA overnight.....