TM 1-1520-253-23
5.8.3.7 Marking and Recording of Inspection Results. Mark and record as required by paragraph
5.8.4 Backup Method. None required.
5.8.5 System Securing. The engine mount adapter, if removed, requires installation in accor-
dance with the applicable technical manuals listed in Table 1-1. Secure the engine upper and lower
doors.
EXHAUST CONE AND STIFFENER (PT).
5.9.1 Description (Figure 5-1, Index No. 9). The exhaust system conducts the exhaust gases in
a smooth flow from the engine to the atmosphere. The exhaust cone (tailpipe) is connected to the
aft end of the engine by a coupling.
5.9.2 Defects. This inspection is to verify cracks found visually. Also to inspect welded repairs.
No cracks are allowed.
5.9.3 Primary Method. Fluorescent Penetrant.
5.9.3.1 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.
5.9.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance.
Partial inspection for cause (visual indications, sites of mechanical damage, corrosion, etc.) may
be performed on all exposed surfaces of the installed part using this procedure. If required, the
exhaust cone shall be removed in accordance with the applicable technical manuals listed in
5.9.3.3 Access. Access is through the engine upper and lower doors from the engine work
platform See Figure 1-4 - CH-47: 20, 21, and 22; MH-47: 18, 20, and 21.
5.9.3.4 Preparation of Part. Refer to Preparation of Part or Area for NDI, paragraph 1.4.4.
5.9.3.5 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 5-9.
5.9.3.6 Marking and Recording of Inspection Results. Mark and record as required by paragraph
5.9.4 Backup Method. None required.
5.9.5 System Securing. Clean the exhaust cone and stiffener to remove inspection media. Refer
to Post Cleaning and Restoration of Part or Area After NDI paragraph 1.4.16. The exhaust cone,
if removed, requires installation in accordance with the applicable technical manuals listed in
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