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 main landing gear trailing arms shall be
removed in accordance with the applicable technical manuals listed in Table 1-1.
Access. Access is from panels (Figure 1-4, Items L140 and R140).
Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,
NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.
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 4-25.
Select AC on the AC/DC power switch.
Place probe/yoke on part in position 1 as shown.
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.
Inspect for cracks using the black light.
Demagnetize before moving to the next position. Refer to paragraph 184.108.40.206.
Repeat steps a. through e. for positions 2 through 5.
Marking and Recording of Inspection Results. Mark and record the inspection results as required by
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.
Backup Method. None required.
System Securing. Clean the main landing gear trailing arms 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 main landing
gear trailing arms, if removed, require installation in accordance with the applicable technical manuals listed in Table 1-1.
4.26 MAIN LANDING GEAR WHEELS (ET).
Description (Figure 4-1. Index No. 26). The main landing gear wheels are two-piece aluminum. The items
typically requiring inspection are the aluminum wheel halves, the valve stem boss, the valve stem hole, threaded areas,
and areas around threaded inserts.
Defects. This inspection is used to verify crack indications found visually on the main landing gear wheels.
No cracks are allowed.
Primary Method. Eddy Current.