ENGINE NOSE GEARBOX (ET).
Description (Figure 3-1. Index No. 11). The engine nose gearbox assembly is mounted on the forward end of
each engine nacelle. The engine nose gearbox assemblies change the drive angle and reduce the engine RPM output to
the main transmission.
Defects. This inspection is used to verify crack indications found visually on the engine nose gearbox. No
cracks are allowed.
Primary Method. Eddy Current.
188.8.131.52 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 aluminum (0.008, 0.020, and 0.040 EDM notches)
Reference Block, three-notched magnesium (0.008, 0.020, and 0.040 EDM notches)
Teflon Tape, refer to Table 1-8
Aircraft Marking Pencil, refer to Table 1-8
3.1 1.3.2 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 engine nose gearbox shall be removed in accordance with the
applicable technical manuals listed in Table 1-1.
184.108.40.206 Access. Access is through the engine nose gearbox fairing (see Figure 1-4, Item LN6 and RN6).
220.127.116.11 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,
18.104.22.168 NDI Equipment Settings.
Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19eII
- 200 KHz