TM 1-1520-253-23
c. Remove markings as soon as there is no further need for them with a low-lint cloth, MIL-C-85043, dampened
with tap water. It is allowable for a shadow of the marking to remain on the surfaces after removal.
WARNING
Cleaning solvents P-D-680, Type II and MIL-C-38736 are flammable. Avoid eye and skin contact or
breathing of vapors. Protective equipment consisting of goggles, gloves, and respiratory
protection is required.
CAUTION
Do not use cleaning solvent MIL-C-38736 on acrylic lacquer, as it may soften finish.
d. Dry-cleaning solvent, P-D-680, Type II shall be used for removal of markings on acrylic lacquer surfaces.
e. Record inspection results as required by the applicable technical manuals listed in Table 1-1.
1.4.1 Purpose of Nondestructive Inspection (NDI). Methods used in NDI are those that may be applied to inspect a
structure or component to determine its ability to perform its intended function without damaging or causing any change
in the characteristics of the structure or component. During manufacture, aircraft components are given in-process and
final inspections. The most commonly used methods are magnetic particle and liquid penetrant because these two
methods are bulk processes that provide 100 percent inspection coverage and they are highly effective. It is unusual, but
possible, for NDI personnel to locate defects that are inherent (associated with the production of the material) or related
to the manufacturing operations. It follows that nearly all maintenance nondestructive inspection requirements are to
locate defects that have developed during service (i.e., corrosion and corrosion induced cracking, fatigue cracks, and
defects resulting from mechanical damage, improper maintenance, or inappropriate use). It is important that NDI
personnel shall be able to distinguish between inherent or in-service defects. A general knowledge of typical sites for in-
service defect occurrence and specific knowledge of the mode and location of previous cracking problems for a particular
part is relevant. This knowledge will assure that the crack prone areas are identified for inspection and time will not be
wasted inspecting areas not subject to in-service cracking.
This manual summarizes the steps necessary to perform satisfactory inspections. It includes the preparation of the
helicopter, the inspection area for NDI, safety rules to be observed, highlights of each inspection method, and specific
safety precautions for each of these methods. For a detailed description of each method and its application, refer to the
Technical Manual, Nondestructive Inspection Methods, TM 55-1500-335-23. Specific procedures peculiar to each part
being inspected will be included in the discussion of that inspection item as it is covered in this manual.
