TM 1-1520-264-23
4.2
FUSELAGE AND EMPENNAGE A CCESS DOORS, COVERS, PANELS, SKINS, AND
FAIRINGS- METAL (ET).
4.2.1
Description (Figure 4-1. Index No. 2).
This inspection is applicable to all access doors, covers, panels, skins, and
fairings constructed of nonferrous metallic materials.
4.2.2
Defects. Defects may occur anywhere on the surface of the components listed above. The primary purpose of
this inspection is for: (1) confirmation of crack indications identified by visual inspections; (2) verifications that dents,
scratches, or gouges do not conceal cracks; and (3) locating the ends of confirmed cracks so that stop drilling may be
performed. 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, 100 KHz-500 KHz
c.
Probe, right angle, shielded surface, 100 KHz-500 KHz, 90
°
1/2 inch drop
d. Cable Assembly
e.
Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)
f.
Reference Block, three-notched magnesium (0.008, 0.020, and 0.040 EDM notches)
g.
Reference Block, three-notched titanium (0.008, 0.020, and 0.040 EDM notches)
h.
Teflon Tape, refer to Table 1-8
i.
Aircraft Marking Pencil, refer to Table 1-8
4.2.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. If required, access
doors, covers, panels, and fairings shall be removed in accordance with the applicable technical manuals listed in Table
1-1.
4.2.3.3 Access. The components are generally accessed from outside the helicopter.
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.
4.2.3.5 NDI Equipment Settings.
a.
Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-1 9e
”.
Frequency F1
- 200 KHz
F2
- off
HdB
- 57.0
VdB
- 69.0
Rot
- (56°
aluminum and magnesium) (30
°
titanium)
Probe drive
- mid
LPF
- 100
HPF
-0
H Pos
- 80%
VPos
- 20%
4-5
