TM 1-1500-204-23-11
b. Hand Sanding. Hand sanding with 180-grit
Lightning strike protection (aluminum or copper
sandpaper on a soft sanding block removes paint
mesh, or aluminum foil) shall never extend
satisfactorily in many applications. However, a light
into the area under the repair patch. Loss of
touch is needed and the sanding block must be
structural integrity may occur.
moved in a direction parallel to the surface ibers to
prevent damage to the surface ply. This technique
Sand only in the direction speciied in the
requires minimal preparation and cleanup time and
system speciic technical manual. Incorrect
costs little. The removal rate is very slow and the
sanding may reduce the life of the component.
process is labor intensive. This is the preferred
Rotor blades are typically sanded in the span
method for sanding small areas.
wise direction if allowed at all.
c. Power Sanding. Paint removal can be per-
6-3. PAINT REMOVAL PROCEDURE. Follow these
formed by a Dual Action (DA) or random orbital
steps for paint removal:
sander; a jitterbug sander, or a 90 die grinder with
a 2 inch sanding mandrel and a Scotchbrite pad.
a.
Preclean the repair area in accordance with para-
As with hand sanding, care should be taken to sand
in the direction of surface ibers as much as possible
to avoid damaging them. Power sanding provides a
b.
Apply masking tape to mask off the repair area
rapid means of paint removal. Extreme care must
and to provide a paint removal boundary. The
be used to prevent gouging and/or damaging more
paint should be removed from an area at least 1-2
material than the needed repair.
inches larger than the repair area in all directions
c.
Remove paint by hand sanding or orbital sander
in accordance with the system speciic technical
Avoid breathing dust from sanding operations.
manual for your repair application.
Use vacuum equipment when it is available.
Wear eye protection during all material removal
d.
Vacuum area frequently to reduce paint residue
operations. As a minimum, wear a dust mask
buildup on the abrasive paper.
and ensure adequate ventilation. Consult with
your local safety ofice for the appropriate per-
e.
Visually inspect the abrasive paper frequently for
sonal protective equipment for your operation.
paint buildup and replace as required.
Use appropriate personal protective equipment
NOTE
while removing and disposing of chromate
primer waste material in accordance with local
Power sand only to the primer. The primer
environmental regulations.
is usually a different color. Hand sand to
the composite material using ine (240-grit or
iner) sandpaper.
f.
When primer is visually detected on the part,
The use of chemical paint stripper is prohibited
change to 240 grit or iner abrasive paper accord-
as it attacks the composite resin system and
ing to the system speciic technical manual and
loss of structural integrity may occur.
continue hand sanding until the majority of the
primer has been removed. Some residual primer
DO NOT sand into laminate when removing
may remain in peel ply impression recesses
paint. When working on a carbon iber lami-
on the laminate surface. It is permissible for a
nate, a black colored dust on the sand paper
residual haze of primer to remain on the laminate
indicates that sanding into the laminate has
surface. Sand cautiously to prevent laminate
occurred and carbon iber is being removed.
damage: some composite parts are painted with
If this occurs, the sanding process should
dark colored primers making primer detection
be stopped immediately. A loss of structural
dificult, and some are painted without the use of
integrity may occur if ibers are exposed or
primer.
damaged. Aluminum oxide and silicon car-
bide sandpaper can be used on all advanced
composite materials. Wet sanding shall not
be performed on a composite laminate.
6-2
