Section 220.127.116.11. NDI Capability Evaluation for Corrosion
The impact of corrosion on the sustainment costs of an aging
fleet is significant, particularly for transport
aircraft. The presence of corrosion
indicates a failure of the corrosion protection system and necessitates
some sort of action in the maintenance plan.
Regardless of the corrosion control maintenance strategy, NDI plays an
important role in its implementation and the need exists to quantify the
corrosion detection capability of the inspection system.
Several types of corrosion
are typically found in aging airframes – uniform, pitting, intergranular,
exfoliation, crevice (uniform and pitting), and stress corrosion cracking. Adaptations of the standard NDI methods
discussed in Subsection 3.1.1 can be used to detect the various types of corrosion damage and new inspection methods are
evolving. Although there is a need to
quantify the corrosion detection capability of an NDI system, at present
there is no commonly accepted procedure for doing so. Approaches to characterizing corrosion detection capability can
be found in Alcott , Howard and Mitchell , Roach ,
Komorowski, et al. , and Hoppe, et al. . This subsection discusses two of the major problems in
quantifying NDI capability for detecting corrosion and describes the method of
Hoppe, et al. .