TM 1-1520-265-23
2-26 Change 3
2.13.3.1 NDI Equipment and Materials. (Refer to Appendix B.)
a. Eddy Current Inspection Unit
b. Probe, straight, shielded surface, 2 MHz (Titanium)
c. Probe, right angle, shielded surface, 2 MHz, 90_ 1/2 inch drop (Titanium)
d. Adapter, Probe
e. Cable Assembly
f. Reference Block, three-notched Aluminum (0.008, 0.020, 0.040 EDM notches)
g. Reference Block, three-notched Titanium (0.008, 0.020, 0.040 EDM notches)
h. Teflon Tape, refer to Table 1-8
i. Aircraft Marking Pencil, refer to Table 1-8
2.13.3.2 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
damper assembly shall be removed in accordance with the applicable technical manuals listed in
Table 1-1.
2.13.3.3 Access. Access to the damper assembly is from the L/R engine cowl (Figure 1-4, Items
3T-7 and 4T-8).
2.13.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to preparation of Part or
Area for NDI, paragraph 1.4.4.
2.12.3.5 NDI Equipment Settings.
a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19eII.
Frequency F1
- 200 KHz (Aluminum) 1500 KHz (Titanium)
Frequency F2
- off
HdB
- 57.0
VdB
- 69.0
Rot
- (56_ Aluminum and Titanium)
Probe drive
- mid
LPF
- 100
HPF
- 0
H Pos
- 80%
V Pos
- 20%
b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:
(1) .Null probe on test block.
(2) .Adjust phase as required to obtain horizontal lift-off.
(3) .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 1-7.)
