TM 1-1520-265-23
4.7.3.3
Access. Remove the drag beam support fairing.
4.7.3.4
Preparation of Part. Refer to Preparation of Part or Area for NDI, paragraph 1.4.4.
4.7.3.5
Inspection Procedure. Perform fluorescent penetrant inspection. Refer to Fluorescent Penetrant Method,
paragraph 1.4.7 and Table 1-5. Inspect area of concern. See Figure 4-7.
4.7.3.6
Marking and Recording of Inspection Results. Mark and record inspection results as required by paragraph
1.3.
4.7.4
Backup Method. None required.
4.7.5
System Securing. Clean the roll vibration absorber to remove inspection media. Refer to Post Cleaning and
Restoration of Part or Area After NDI, paragraph 1.4.16. The roll vibration absorber, if removed, requires installation in
accordance with the applicable technical manuals listed in Table 1-1.
4.8
ALUMINUM STRUCTURAL BEAMS AND FRAMES (ET).
4.8.1
Description (Figure 4-1, Index No. 8). The primary airframe structure is aluminum alloy. This procedure can
be used on all-aluminum beams and frames as well as aluminum skin panels and doors.
4.8.2
Defects. This inspection is used to verify crack indications found visually on the aluminum structural beams
and frames. No cracks are allowed.
4.8.3
Primary Method. Eddy Current.
4.8.3.1
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, 0.040 EDM notches)
f.
Teflon Tape, refer to Table 1-8
g.
Aircraft Marking Pencil, refer to Table 1-8
4.8.3.2
Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance in accordance with
the applicable technical manuals listed in Table 1-1.
4.8.3.3
Access. Generally easily accessed. If required, see Figure 1-4 and Table 1-2.
4.8.3.4
Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,
paragraph 1.4.4.
4-19
