Change 23 7-17
If cracks are suspected, refer to TM
1-1520-254-23, Technical Manual Aviation
Unit Maintenance (AVUM) and Aviation Inter-
mediate Maintenance (AVIM) Manual Nonde-
structive Inspection Procedure for OH-58 He-
a. Vane Damage. Replace the compressor case if
any vanes are cracked or broken off or show evidence of
tip rub on the rotor spacer. Blend limits for the vanes are
Leading and Trailing Edge Damage. Re-
place the compressor case if damage to the leading and
trailing edge cannot be blended out without reducing the
total width of the vane more than the limits given in figure
7-13. Replace the compressor case when after blending,
the vane total width is reduced more than the limits given
in figure 7-13 or there are sharp edges, burrs, cracks or
tears after blending.
Surface Damage. (See figure 7-13.) Blend
and polish surface damage on the vanes. Replace the
compressor case when: (1) the blending depth exceeds
chord width less than the acceptable chord width (B).
(See figure 7-3.)
Corrosion. Blend and polish to remove cor-
rosion pitting. Replace the compressor case when pitting
in any area of the vane forms a definite line or blending
exceeds same limits as given for blades. (see figure
b.Compressor Case Painting.
case external surface is painted with gray, corrosion re-
sistant paint. Repair damaged paint on the external sur-
face of the compressor case as follows:
(1)Abrade the damaged area and localized sur-
rounding area with emery cloth (item 23, table 2-2).
(2)Wipe abraded area with paint thinner (item
24, table 2-2) .
(3)Apply gray corrosion resistant paint (item 25,
table 2-2) to the abraded area.
(4)Air dry at least one hour before handling.
Figure 7-13. Compressor Stator Vane Blend Limits
c. Visual dents in compressor case sheet metal skin.
Serviceable limits are as follows: 0.010 in. max.
depth, 0.125 in. max. diameter, dents may have a
smooth round bottom. Repairable Limits: Dents can be
straightened to original contour. If the repairable limits
1/2 of the vane thickness or (2) cracking is detected on
the vane surface.
(3) Erosion. Replace the compressor case
when vane erosion at a specified stage results in a vane
are exceeded replace the case assembly.