TM 1-1520-253-23
a. Place probe on part in the inspection locations 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 is cause for rejection.
NOTE
Either probe identified in paragraph 6.9.3.1 may be used depending primarily on
the ease of accessibility and user friendliness. If the probes are changed, steps
6.9.3.5 b.(1), (2), and (3) shall be repeated each time a change is made.
6.9.3.7 Marking and Recording of Inspection Results. Mark and record as required by paragraph
6.9.4 Backup Method. None required.
6.9.5 System Securing. The part requires assembly and installation in accordance with the
applicable technical manuals listed in Table 1-1.
FLIGHT CONTROL RESERVOIRS/COOLERS AND RELATED EQUIPMENT (PT).
6.10.1 Description (Figure 6-1, Index No. 10). This procedure is primarily for the flight control
reservoir/cooler, but it can also apply to accumulators, the power transfer unit, and hydraulic pump
casings.
6.10.2 Defects. This inspection is to verify cracks found visually.
6.10.3 Primary Method. Fluorescent Penetrant.
6.10.3.1 NDI Equipment and Materials. Inspection equipment shall be selected from the approved
list in Table 1-7, and AMS-2644 level 3 penetrant materials shall be selected from the approved list
in Table 1-8. Parts requiring fluorescent penetrant inspection shall be cleaned prior to inspection
with n-Propyl Bromide (vapor degreasing only) (Table 1-8), DS-108 (Table 1-8). DS-108, Electron,
Positron must be followed by an Acetone (Table 1-8) or Isopropyl Alcohol (Table 1-8) rinse or wipe;
or drying until there is no visible solvent residue left on parts.
6.10.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance.
If required, the components shall be removed in accordance with the applicable technical manuals
listed in Table 1-1.
6.10.3.3 Access. Access from the forward or aft transmission work platforms. See Figure 1-4 -
CH-47: 9, 27, and/or 34: MH-47: 16 and 17.
6.10.3.4 Inspection Procedure. Perform fluorescent penetrant inspection. Refer to Fluorescent
Penetrant Method, paragraph 1.4.7 and Table 1-4. Inspect area of concern. See Figure 6-10.
6.10.3.5 Marking and Recording of Inspection Results. Mark and record as required by paragraph
6.10.4 Backup Method. None required.
6.10.5 System Securing. Clean the part to remove inspection media. Refer to Post Cleaning and
Restoration of Part or Area After NDI, paragraph 1.4.16. The components, if removed, require
installation in accordance with the applicable technical manuals listed in Table 1-1. Secure the
forward and aft transmission work platforms.
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