4.31 MAIN LANDING GEAR SHOCK STRUT MOUNT SHAFT (MT). (Per TB 1-1520-238-20-81)
Description (Figure 4-1. Index No. 31)
. The main landing gear shock strut mount shaft projects from the
fuselage and the main landing gear shock strut is attached to it. There is one for each main landing gear.
Defects. This inspection is used to verify crack indications found visually on the main landing gear shock
strut mount shaft. No cracks are allowed.
Primary Method. Magnetic Particle.
NDI Equipment and Materials. (Refer to Appendix B.)
Hand-held Magnetic Coil
Fluorescent Magnetic Particles, refer to Table 1-8
Consumable Materials, refer to Table 1-8
Aircraft Marking Pencil, refer to Table 1-8
Hand-held magnetic coil may be used. Refer to paragraph 220.127.116.11.2 and Figure 1-6.
Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the main
landing gear shock strut removed in accordance with the applicable technical manuals listed in Table 1-1.
Access. Not applicable.
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. The position required for this inspection are illustrated in Figure 4-31.
Place coil on part 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.
Marking and Recording of Inspection Results. Mark and record the inspection results as required by
Demagnetization. Place the coil in the same position used for magnetizing. Press the test switch and
withdraw the coil from the part for a distance of two feet before releasing the switch.