TM 1-1520-253-23
5.5.4 Backup Method. Fluorescent Penetrant, refer to paragraph 1.4.7.
5.5.5 System Securing. The engine mount structure, if removed, requires installation in accordance with the applicable
technical manuals listed in Table 1-1. Secure the engine upper and lower doors.
AFT ENGINE MOUNT LINK (MT).
5.6.1 Description (Figure 5-1, Index No. 6). The aft engine mount link connects the engine adapted, to the aft engine
mount lugs on the structure.
5.6.2 Defects. This inspection can be used at any time but is primarily used to verify cracks found
visually during excessive G-force load inspections.
5.6.3 Primary Method. Magnetic Particle.
5.6.3.1 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
5.6.3.2 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 aft engine mount link shall be removed in accordance with the
applicable technical manuals listed in Table 1-1.
5.6.3.3 Access. Access is through the engine upper and lower doors from the engine work platform. See Figure 1-4 - CH-
47: 20, 21, and 22; MH-47: 18, 20, and 21.
5.6.3.4 Preparation of Part. The aft engine mount link shall be thoroughly cleaned. Refer to Preparation of Part or Area
for NDI, paragraph 1.4.4.
5.6.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.
5.6.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of possible
cracks. Positions required for this inspection are illustrated in Figure 5-6.
a. Select AC on the AC/DC power switch.
b. Place probe/yoke on part in Position 1 as shown.
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.
e. Demagnetize before moving to the next position. Refer to paragraph 5.6.3.8.
f.
Repeat steps a. through e. for Positions 2 and 3.
5-12
