TM 1-1520-265-23
Change 3
3-15
3.7.3.2 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 oil
cooler drive shaft shall be removed in accordance with the applicable technical manuals listed in
Table 1-1.
3.7.3.3 Access. Access is obtained through the oil cooler access panels (Figure 1-4, Item 3T-25).
WARNING
Maintenance Platforms/Workstands
Use only appropriate platforms, workstands, or other approved locally procured
stands and restraint equipment when working above 10 feet on helicopters in a
nontactical environment. Otherwise, personnel injury could result from accidental
falls.
3.7.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or
Area for NDI, paragraph 1.4.4.
3.7.3.5 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 Ttanium)
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.)
3.7.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 3-7.
a. Place probe on a good area in the inspection location and null. Adjust phase as required to
obtain horizontal lift-off.
b. Inspect the part.
c. Any signal similar to the notches in the test block are cause for rejection.
