TM 1-1520-265-23
Change 2 1-31
Film processing is a series of operations such as developing, fixing, and washing, associated with
the conversion of the latent image into a stable visible image and will be provided by manual or
automatic film processing.
1.4.10.1 Safety precautions During Radiographic Inspections. Follow safety precautions and
instructions contained in this manual and the Nondestructive Inspection Methods manual listed in
Table 1-1.
WARNING
Radiation Hazard
Assure compliance with all applicable precautions set forth in TM 1-1500-335-23
(Nondestructive Inspection Methods manual) listed in Table 1-1. A hazard associated
with exposure to ionizing radiation is that serious injury can be inflicted without pain,
burning, or other sense of discomfort during the exposure period. Radiation protection
shall be utilized in accordance with AR40-14/DLAR 1000.28.
1.4.10.2 Mixing of Radiographic Film Processing Chemicals. Exercise extreme care when working
with film processing chemicals. Fixer solution is highly acidic and developer is highly caustic. Avoid
contact with the skin. Flush any skin contact with water.
1.4.11 Eddy Current (ET) Method.
NOTE
Eddy current inspections shall be performed in accordance with the general
application and techniques in TM 1-1500-335-23 (Nondestructive Inspection Methods
manual) and the specific requirements of this technical manual.
The eddy current method is used for discontinuities in electrically conductive materials. The method
is effective when inspecting for discontinuities originating: (1) at the radii of mounting lugs, flanges,
or crevices; (2) at pressed-in (interference fit) grease fittings, guide pins, etc.; and (3) from fastener
holes and bushing/bearing bores. Eddy current method will locate surface cracking on any
conductive material, but probes and techniques for inspection of magnetic materials may differ
considerably from those used on nonferromagnetic materials.
Eddy current has great value for inspecting areas where paint stripping is not desirable and/or
impossible. The method also has wide application in confirming surface indications found by other
methods.
The capability and versatility of the eddy current method has been greatly enhanced by the use of
modern phase analysis (impedance plane display) instruments used in conjunction with shielded
probes. These instruments display a representation of the impedance plane which illustrates both
the magnitude and direction of impedance changes. Impedance variables (conductivity, probe
lift-off, permeability variations, etc.) can be separated by their characteristic video response and are
readily recognized by the trained operator. The interaction of the probe coils and the part is
represented by a “flying spot” (or dot) in the video display.
