TM 55-2840-241-23
Change 19 7-5
d.
Insect for nicks, dents, and erosion on the blade
leading and trailing edges and at the blade tip. All dam-
age and imperfections must be blended out. (Refer to
paragraph 7-24 a and b.) Blended leading and trailing
edges, and chamfered blade tips must not exceed the
limits shown on figures 7-10 and 7-11.
e.
Inspect the blade tips and leading edges for evi-
dence of loose plastic rub on all blades in a given stage.
Loose plastic rub is a result of the compressor case plas-
tic lining coming loose, and displacing inward, wearing
away portions of all blades in a given stage. Loose plastic
rub is evidenced as a chamfer at the leading edge tip or
an undercut of the blade leading edge. (See figure, 7-2.)
Replace the engine if rub is indicated.
f.
Inspect the blade tips for heat discoloration on one
or more blades. Heat discoloration is caused by severe
blade rub on the compressor case plastic lining which
occurs when the wheels shift off center due to an unbal-
ance condition. Replace the engine if heat discoloration
is detected.
7-10. Compressor Stator Vane Inspection.
Visually inspect the compressor stator vanes for the
following conditions. Replace both compressor case
halves if any of the limits are exceeded.
NOTE
This inspection requires removal of a com-
pressor case half and shall be performed only
for the reasons stated in paragraph 6-2.
a.
Inspect for cracked or missing stator vanes -
none are permitted. If cracks are suspected in the stator
vanes, refer to TM 1-1520-254-23, Technical Manual Avi-
ation Unit Maintenance (AVUM) and Aviation Intermedi-
ate Maintenance (AVIM) Manual Nondestructive Inspec-
tion Procedure for OH-58 Helicopter Series.
b.
Inspect the vane tips for evidence of rub. Rub is
indicated by smeared metal on the vane tip associated
with a burr on the convex side or by heat discoloration on
the vane. Replace the engine if rub is indicated.
c.
Insect for evidence of corrosion on the vanes.
Pitting in any area of the vane that forms a definite line
is not acceptable. Replace the compressor case if pitting
exceeds blend limits. (Refer to paragraph 7-25 a.)
d.
Inspect for erosion on the airfoil leading and trail-
ing edges. Replace the compressor case if the limits of
figure 7-3 are exceeded.
e.
Inspect for nicks, and dents on the vane and trail-
ing edges. All damage and imperfections must be
blended out. (Refer to paragraph 7-25 a.) Blended lead-
ing and trailing edges must not exceed the limits shown
on figure 7-13.
f.
Insect for nicks and dents on the vane airfoil sur-
face. All damage and imperfections must be blended out.
Refer to paragraph 7-25 a.) Blended areas must be with-
in the limits shown on figure 7-13.
g.
Inspect for bent vanes. Straighten vanes that are
bent on the inner three-fourths of the vane. Vanes that
are bent on the outer one-fourth are not acceptable.
7-11. Compressor Plastic Coating Inspection.
Visually inspect the compressor case plastic coating
for the following conditions. Replace both compressor
case halves if any of the limits are exceeded.
Figure 7-2. Compressor Blade Damage Caused by Rub
