5.2 AFT INBOARD AND AFT LOWER ENGINE MOUNTS (ET).
Description (Figure 5-1. Index No. 2)
. The aft inboard and aft lower mounts are made of titanium and attach
to the diffuser case. This task is applicable to both mounts on both engines.
Defects. This inspection is used to verify crack indications found visually on the engine mounts. No cracks are
Primary Method. Eddy Current.
NDI Equipment and Materials. (Refer to Appendix B.)
Eddy Current Inspection Unit
Probe, straight, shielded surface, 100 KHz-500 KHz
Probe, right angle, shielded surface, 100 KHz-500 KHz, 90
1/2 inch drop
Reference Block, three-notched titanium (0.008, 0.020, and 0.040 EDM notches)
Teflon Tape, refer to Table 1-8
Aircraft Marking Pencil, refer to Table 1-8
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 engine mounts shall be removed in accordance with the
applicable technical manuals listed in Table 1-1.
Access. Access is through the engine door (Figure 1-4, Items R/L N3 and N4).
Preparation of Part. The part shall be thoroughly cleaned
. Refer to Preparation of Part or Area for NDI,
NDI Equipment Settings.
Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19ell.
- 200 KHz
Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:
Null probe on test block.
Adjust phase as required to obtain horizontal lift-off.
Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when
probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure