TM 9-4940-568-20
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2-24. GENERAL INSPECTION INSTRUCTIONS (CONT).
e.
Metal Parts. Visually inspect all castings and weldments for cracks. Parts that carry a great load should
receive magnetic particle inspection. Critical non-ferrous parts may be inspected with fluorescent penetrant.
f.
Drain Plugs. When removing drain plugs from engine and hydraulic system, check amount of sediment on
plugs. Accumulations of grit or fine metal particles may indicate actual or potential component failure. A few fine
particles are normal. This inspection helps to determine if there are defective parts prior to internal inspection of
the component and to predict degradation of the equipment.
2-25. GENERAL REPAIR INSTRUCTIONS.
a.
Screws, Nuts and Fittings. Replace any screw, nut, or fitting with damaged threads. Inspect tapped holes
for thread damage. If cross-threading is evident retap the hole for the next oversize screw or stud. If the retapping
will weaken the part, or if the cost of the part makes retapping impractical, replace the part. Chasing the threads
with proper size tap or die may be adequate.
b.
Sheet Metal Repair. Repair minor skin cracks by installing patches.
2-26. GENERAL ASSEMBLY INSTRUCTIONS.
a.
Preparation. Remove protective grease coatings from new parts before installation.
b.
Preformed Packing Installation. Lubricate all preformed packings with a thin coat of lubricating oil
(Item 24, Appendix C) before installing. To install a preformed packing, first clean the groove, then stretch
packing and place into position. Place component on flat surface and uniformly press packing into position.
Ensure preformed packings are not nicked or torn during assembly.
Use sealing compound sparingly and only on male threads. Do not apply compound on first
two threads to avoid contamination of system from compound. Do not apply compound to
hose connections or fittings with preformed packings. Damage to equipment may result.
c.
Pipe Joints and Fittings. Use sealing compound, sealant, or adhesive as indicated in each maintenance
task.
d.
Oil Seals. Coat oil seals evenly with oil or grease before installing. Install oil seals with seal lip facing
toward lubricant, applying an even force to outer edge of seal. If oil seals are to be installed over keyed or
splined shafts, use a guide to prevent sharp edge of keyway or splines from cutting the leather or neoprene seal.
Construct guides of very thin gauge sheet metal and shape to the required diameter. Make certain guide edges
are not sharp and are bent slightly inward so they do not cut the seal.
