But if Bell were really concerned, they could at least have insisted on removal and NDT of the SCs in question - rather than waiting for cracks to propagate - seems to me that they weren't that worried about wingovers causing the problem.
The sloping ground landings, on the other hand, are far more likely to have been a causal factor since the bending stresses on all the MRGB components are obvious and with student mishandling, likely to exceed design tolerances far more easily and far more often.