Meanwhile - out in the real world..., page-5

On page 7 of the report:
"In order to properly consider the effects of crack closure in an unloaded condition (i.e. during sensor monitoring), a crack was deemed to be detected when a permanent alarm was produced and the CVM sensor did not maintain a vacuum even if the fatigue stress was reduced to zero. Crack detection lengths ranged from 0.145” to 0.245” in length for the wing box fitting application. The crack detection lengths correspond to permanent alarm levels for cracks engaging CVM sensors with the structure in an unloaded condition."