TM 1-1520-253-23
ROTARY-WING HEAD (MT).
2.2.1 Description (Figure 2-1. Index No.2). This inspection is applicable to all surfaces of the webs, lugs, and holes of
the rotary-wing head to verify indications found visually.
2.2.2 Defects. Defects may occur anywhere on the surface of the part. No cracks are allowed.
2.2.3 Primary Method. Magnetic Particle.
2.2.3.1 NDI Equipment and Materials. (Refer to Appendix B.)
a. Magnetic Particle Inspection Probe/Yoke
b. Magnetometer
c. Black Light
d. Fluorescent Magnetic Particles
e. Consumable Materials, refer to Table 1-8
f. Aircraft Marking Pencil, refer to Table 1-8
2.2.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. 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 rotary-wing head shall be removed in accordance with the applicable
technical manuals listed in Table 1-1.
2.2.3.3 Access. Access is from the forward and aft transmission work platforms. See Figure 1-4 CH-47: 9, 27, and/or
34; MH-47: 16 and 17.
2.2.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,
2.2.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.
2.2.3. 6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of possible
cracks. Position for this inspection is illustrated in Figure 2-2.
a. Select AC on the AC/DC power switch.
b. Place probe/yoke on part as shown in relation to suspect crack.
c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media
momentarily before removing the current. Current should be applied for no more than five seconds.
d. Inspect for cracks using the black light.
2.2.3.7 Marking and Recording of Inspection Results.
Mark and record the inspection results as necessary per
2-3
