That repair
We've seen two theories advanced in previous posts that suggest a possible link between the accident and the 2012 wingtip incident and/or subsequent repair:
a) that the ground collision at Pudong caused undetected damage elsewhere in the wing structure that led to an incipient, possibly fatigue-related, subsequent failure
b) that an eventual failure of the repair itself led to aeroelastic flutter, which in turn caused the wing to fail
Personally, I don't buy (a), but either could account for the sudden inability of the crew to aviate, navigate or communicate.
Is there an aerodynamicist in the house?