Section 3.1.1.1. 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.