lomapaseo
you write....
"I'm still not clear what the critical safety issue is that caused the grounding of this fleet."
You must have not read the Airworthiness Directive..... The FAA seem pretty clear.
You read it? Then are you second guessing the RA (Regulating Authority)? As in hand as FAA are, one would expect it took more evidence than necesssary to ground, not less?
Clarify?