TM 1-1520-265-23
4-50 Change 2
4.21 STABILATOR ACTUATOR HOUSING (PT).
4.21.1 Description (Figure 4-1, Index No. 21). The hydraulically-operated actuator is mounted to
the pylon and the horizontal stabilator. It reacts to commands from the cockpit and moves the
horizontal stabilator in an up or down direction.
4.21.2 Defects. This inspection is used to verify crack indications found visually on the actuator
housing. No cracks are allowed.
4.21.3 Primary Method. Fluorescent Penetrant.
4.21.3.1 NDI Equipment and Materials. (Refer to Appendix B.) Inspection equipment is listed in
Table 1-7. AMS 2644 level 3 penetrant materials shall be selected from the approved list in Table
1-8. Parts requiring flourescent penetrant inspection shall be cleaned prior to inspection with
n--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) rinse
or wipe: or drying until there is no visible solvent residue left on parts..
4.21.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance
and the actuator removed in accordance with the applicable technical manuals listed in Table 1-1.
4.21.3.3 Access. Not applicable.
4.21.3.4 Preparation of Part. Refer to Preparation of Part or Area for NDI, paragraph 1.4.4.
4.21.3.6 Inspection Procedure. Perform fluorescent penetrant inspection. Refer to Fluorescent
Penetrant Method, paragraph 1.4.7 and Table 1-5. Inspect area of concern. See Figure 4-21.
4.21.3.7 Marking and Recording of Inspection Results. Mark and record inspection results as
required by paragraph 1.3.
4.21.4 Backup Method. None required.
4.21.5 System Securing. Clean the actuator to remove inspection media. Refer to Post Cleaning
and Restoration of Part or Area After NDI, paragraph 1.4.16. The actuator requires installation in
accordance with the applicable technical manuals listed in Table 1-1.
4.22 DRAG BEAM SUPPORT FITTING (ET).
4.22.1 Description (Figure 4-1, Index No. 22). The drag beam support fitting connects the main
landing gear drag beam to each side of the fuselage midsection.
4.22.2 Defects. This inspection is used to verify crack indications found visually on the support
fitting, especially at the lug areas and bearing bores. No cracks are allowed.
4.22.3 Primary Method. Eddy Current.
