When does it become a cover-up vs "oopsie, didn't know"?

If he had dismantled the plane before the FAA knew about the crash, would that still qualify as destroying evidence?

Chopping up the plane and distributing the pieces in assorted different regular trash bins over time sounds like mens rea to me

As far as I understand in the aviation world the expectation is that you tell the FAA after any incident, nevermind crash, and presumably wait for their guidance on the wreck.