TM 1-1520-264-23
4.5.3.7
Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph
1.3.
4.5.4
Backup Method. Fluorescent Penetrant, refer to paragraph 1.4.7.
4.5.5
System Securing. The fittings, castings, and forgings, if removed, require installation in accordance with the
applicable technical manuals listed in Table 1-1.
4.6 TRANSMISSION DECK (ET).
4.6.1
Description (Figure 4-1. Index No. 6).
The transmission deck is found below the transmission. It separates the
transmission compartment from the lower-fuselage. The transmission struts are affixed directly to the transmission deck.
The catwalk, which is over the aft portion of the deck, is a four-piece platform (one piece includes a folding structure) that
covers the drive shaft area.
4.6.2
Defects. This inspection is used to verify crack indications found visually on the transmission deck. No cracks
are allowed.
4.6.3
Primary Method. Eddy Current.
4.6.3.1 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 (0.08, 0.020, and 0.040 EDM notches)
f.
Teflon Tape, refer to Table 1-8
g.
Aircraft Marking Pencil, refer to Table 1-8
4.6.3.2 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
installed part using this procedure. If required, the catwalk shall be removed in accordance with the applicable technical
manuals listed in Table 1-1.
4.6.3.3 Access. Access is through the main rotor transmission panel, hydraulic heat exchanger fairings, and deck area
doors and fairings (Figure 1-4, Items T250L, T250R, T290L, L200, R200, and L325).
4.6.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,
paragraph 1.4.4.
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