The Air India is as F14 says, a carbon copy: the squawk disapeared from radar, as did the AF447, no 7700 was picked up and ZERO mayday calls were made..
If the crew where battling severe turbulence at the time i would say that Sq 7700 was the last thing on there minds.
Ironic if it turns out the pitot system iced up.
Or completely removed from the airframe.
It is more than blausable that the crew where doing everything right regards working there way through a line of CB's only to fly under a anvil, and i am sure most of us have seen the results of what heavy hail can do to a airframe. and it would more than account for the signals sent to AF, as well as leaving little time for the crew to react as systems failed before the aircraft become unflyable.