The specific set of guidelines for intact structure depends upon the capability of the depot level inspection.  Since this example has assumed the situation where the normal inspection can detect less than a failed load path, this case will be examined first.

The intact requirement is that the in-service damage, assumed to be present following the depot level inspection (Figure 1.3.17), shall not grow and cause failure of the major load path (panel ­) before the next opportunity to discover the damage, i.e., the next inspection.

Since this is merely a one-time design requirement, not specifically intended for safety, it is not necessary to account for prior service at the time at which the requirement was imposed.  Thus, the structure is considered as “new” and no incremental growth Da due to prior service is computed.  Figure 1.3.18 illustrates schematically the residual strength and growth guidelines that must be met for the intact structure.

Figure 1.3.18.  Illustration of Damage-Growth Limits and Residual-Strength for Intact Structure Following Depot or Base-Level Inspection for Less-Than-Failed Load Path