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AFGROW | DTD Handbook

Handbook for Damage Tolerant Design

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Section Visual Inspection

In a sense, all inspections in which the find/no find decision is made by a human are visual.  However, in categorizing NDI methods, visual inspections are generally interpreted as inspections in which the inspector is aided, at most, by optical devices, such as magnifying glasses and mirrors.  In the context of JSSG-2006, the in-flight evident, ground evident, walk-around evident, and special visual inspections are all visual inspections and play an important role in the maintenance of structural integrity through damage tolerance.

Visual inspections are the most common and the most economical of the inspections to perform.  However, visual inspections are also the least reliable in terms of the size of the cracks that can be detected.  Since the efficacy of visual inspections is highly dependent on the alertness and acuity of the inspector, an additional level of human factors is introduced in discerning the physical attributes of a crack from its environment.