62-40 Inspection of Main Rotor Blades (continued)
A. Measuring Damage
1. Refer to Figure 62-9. Measure blade damage using a straight edge and a thickness
gage. Keep straight edge parallel with the leading and trailing edges.
2. If blades are installed on the helicopter, measure damage using the shortest straight
edge possible to span damaged area. Using a straight edge of excessive length will
cause a false reading due to natural droop of the blade.
B. Measuring Material Removed After Repair
1. Use calipers or micrometers and compare measurements before and after repair to
estimate amount of material removed.
2. Use a straight edge and thickness gage to measure repaired areas less than 2
inches across in the blade skins and spar.
62-41 Scratches and Corrosion
A. Skins and Doublers
1. Refer to § 62-50 for repair procedures. Polish out damage by hand with a 0.10
inch minimum blend radius.
2. Refer to § 62-40 for measuring damage and measuring material removed after
repair. Repair may not exceed the following limits:
a. 3.0 inch maximum diameter.
b. 3.0 inch minimum distance from another repaired area.
c. 0.012 inch maximum depth between RS 174.0 and RS 198.0.
d. 0.008 inch maximum depth between RS 18.7 and RS 174.0.
3. When recording repair(s), indicate upper or lower blade surface, diameter, depth,
and rotor station location (span and chord).
JUL 2020 Chapter 62 Main Rotor Page 62.19
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