3.17.3 Primary Method. Eddy Current.
Eddy Current Inspection Unit
Probe, straight, shielded surface, 100 KHz-500 KHz
Probe, right angle, shielded surface, 100 KHz-500 KHz, 901/2 inch drop
Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)
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 transmission shall be removed in accordance with the
Access. Access is from the aft transmission work platform. See Figure 1-4 - CH-47: 27 and/or 34; MH-47:
Preparation of Part. The aft transmission outside surface shall be thoroughly cleaned. Refer to Preparation
NDI Equipment Settings.
Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e .
- 200 KHz
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. (Refer to standard instrument display shown