TM 55-1520-240-23-4
5-63.1
ROTARY-WING BLADE SERVICEABILITY INSPECTION (Continued)
5-63.1
1.
The following terms and definitions are used in
determining serviceability of rotary-wing blades:
a.
Bond Voids — Open areas in which one
or more layers of material are not bonded
together by adhesive. Obvious bond voids
appear as slightly raised surfaces, shallow air
bubbles, or free edges. Other bond voids are
only detectable by coin tapping.
b.
Ply Separations — Openings between
adjacent layers of fiberglass skin. Ply
separations resemble bond voids.
c.
Score — A blemish more severe than a
scratch.
d.
Sharp Dent — A depression in which a
definite vee can be seen or felt.
e.
Coin Tapping — An inspection method in
which a coin or metal disk is used to detect
bond voids. When tapped, a bonded area will
have a sharp solid sound. Unbonded areas
will give a dull thud.
f.
Minor Damage — Damage which does not
require repair as described in step 6.
g.
Repairable Damage — Damage which
requires repair as described in step 6.
h.
Non-Repairable Damage — Damage which
requires repair beyond the scope of this
manual. Requires replacement of rotary-wing
blade.
2.
Protect the blade around the suspected damaged
area. Mask surrounding area with barrier
material (E80). Secure barrier material with
masking tape (E388).
WARNING
Acetone (E20) is extremely
flammable. It can be toxic. Avoid
inhaling. Use only with adequate
ventilation. Avoid contact with skin,
eyes, or clothing. Keep away from
heat, sparks, or open flame. In case
of contact, immediately flush skin or
eyes for at least 15 minutes. Get
medical attention for eyes.
3.
Remove finish from suspected damaged area.
Use cloth (E120) damp with acetone (E20). Wipe
with clean dry cloth (E120). Repeat as required.
4.
Examine areas having a contrasting lighter
color. Lighter color indicates unbonding or ply
separation.
5.
If damage is found, repair blade as directed in
step 6. If no damage is found, go to step 7.
NOTE
When operating aircraft in
geographical areas where excessive
rotor blade erosion will occur, refer
to TB 1-1615-351-23 for anti-erosion
tape application instructions.
Change 2
5-277
