TM 1-1520-264-23
3.26.3.2
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 applicable positions of this procedure. If required, the tail rotor gearbox forward and
aft strut fittings shall be removed in accordance with the applicable technical manuals listed in Table 1-1.
3.26.3.3
Access. Access is through the tail rotor transmission fairing (Figure 1-4, Item L546).
3.26.3.4
Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,
paragraph 1.4.4.
Maintenance Platforms/Workstands
Use only appropriate platforms, workstands, or other approved locally procured stands
and restraint equipment when working above 10 feet on helicopter in a nontactical
environment. Otherwise, personnel injury could result from accidental falls.
3.26.3.5
NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.
3.26.3.6
Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of
possible cracks. Positions required for this inspection are illustrated in Figure 3-26.
a.
Select AC on the AC/DC power switch.
b.
Place probe/yoke on part in position 1 as shown.
c.
Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media
momentarily before removing the current. Current should be applied for no more than five seconds.
d.
Inspect for cracks using the black light.
e.
Demagnetize before moving to the next position. Refer to paragraph 3.26.3.8.
f.
Repeat steps a. through e. for position 2.
3.26.3.7
Marking and Recording of Inspection Results. Mark and record the inspection results as required by
paragraph 1.3.
3.26.3.8
Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same
position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet
before releasing the switch.
3.26.4
Backup Method. None required.
3.26.5
System Securing. Clean the tail rotor gearbox forward and aft strut fittings thoroughly to remove all residual
magnetic particle media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The tail
rotor gearbox forward and aft strut fittings, if removed, require installation in accordance with the applicable technical
manuals listed in Table 1-1.
3-60
