TM 1-1520-265-23Change 2 4-694.29 PARKING BRAKE VALVE COMPONENTS (PT).4.29.1 Description(Figure 4-1, IndexNo.29) . The parking brake valve traps fluid pressure to thebrakes to prevent helicopter movement. This inspection pertains to the components containedwithin the parking valve body.4.29.2 Defects. This inspection is used to verify crack indications found visually on the parkingbrake valve components. No cracks are allowed.4.29.3 PrimaryMethod . Fluorescent Penetrant.4.29.3.1 NDI Equipment and Materials. (Refer to Appendix B.) Inspection equipment is listed inTable 1-7. AMS 2644 level 3 penetrant materials shall be selected from the approved list in Table1-8. Parts requiring flourescent penetrant inspection shall be cleaned prior to inspection withn--Propyl Bromide (vapor degreasing only)(Table 1--8), DS--108 (Table 1--8), Electron (Table 1--8),Positron (Table 1--8). DS--108, Electron, Positron must be followed by an acetone (Table 1--8) rinseor wipe: or drying until there is no visible solvent residue left on parts.4.29.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenanceand the parking valve removed and disassembled in accordance with the applicable technicalmanuals listed in Table 1-1.4.29.3.3 Access. Not applicable.4.29.3.4 Preparation of Part. Refer to Preparation of Part or Area for NDI, paragraph 1.4.4.4.29.3.5 Inspection Procedure. Perform fluorescent penetrant inspection. Refer to FluorescentPenetrant Method, paragraph 1.4.7 and Table 1-5. Inspect area of concern. See Figure 4-29.Figure 4-29. Parking Brake Valve Components
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