TM 1-1520-265-23
4-4 Change 3
4.2 AIRFRAME SKIN, PANELS, DOORS, COVERS, AND FAIRINGS - METAL (ET).
4.2.1
Description (Figure 4-1, Index No. 2). This inspection is applicable to all skins, panels,
doors, covers, and fairings constructed of nonferrous metallic material throughout all airframe
sections of this helicopter.
4.2.2
Defects. This inspection is used to verify crack indications found visually on the part being
inspected. No cracks are allowed.
4.2.3
Primary Method. Eddy Current.
4.2.3.1 NDI Equipment and Materials. (Refer to Appendix B.)
a. Eddy Current Inspection Unit
b. Probe, straight, shielded surface, 2 MHz (Titanium)
c. Probe, right angle, shielded surface, 2 MHz, 90_ 1/2 inch drop (Titanium)
d. Probe, Adapter
e. Cable Assembly
f. Reference Block, three-notched aluminum (0.008, 0.020, 0.040 EDM notches)
g. Reference Block, three-notched titanium (0.008, 0.020, 0.040 EDM notches)
h. Reference Block, three-notched magnesium (0.008, 0.020, 0.040 EDM notches)
i. Teflon Tape, refer to Table 1-8
j. Aircraft Marking Pencil, refer to Table 1-8
4..2.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance.
A partial inspection for cause (visual indications, sites of mechanical damage, corrosion, etc.) may
be performed on all exposed surfaces of the part using this procedure. If required, the airframe skin,
panels, doors, covers, and fairings - metal shall be removed in accordance with the applicable
technical manuals listed in Table 1-1.
4.2.3.3 Access Not applicable.
WARNING
Maintenance Platforms/Workstands
Use only appropriate platforms, workstands, or other approved locally procured
stands and restraint equipment when working above 10 feet on helicopters in a
nontactical environment. Otherwise, personnel injury could result from accidental
falls.
4.2.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or
Area for NDI, paragraph 1.4.4.
