Technical data

CHAPTER 3
SURFACE PREPARATION AND CHEMICAL PREPAINT
SURFACE TREATMENT
3.1 SURFACE PREPARATION FOR PAINTING AND
CHEMICAL PREPAINT SURFACE TREATMENT.
The life of an organic coating system, its effectiveness and the
appearance of organic finishes depend more on the condition
of surfaces receiving them than any other factor. Most
surfaces can be expected to present adverse painting condi-
tions due to either the inherent nature of the material, the
environment in the presence of foreign materials, contamina-
tion, or corrosion. Presence of any of these factors will
require treatment or removal action to make possible the
proper application of organic coatings. The life and effective-
ness of organic coatings are an integral part of corrosion
prevention and control for aerospace equipment. These pro-
cedures are for preparation of interior or exterior surfaces that
have existing coating systems to be re-coated or repaired.
These procedures are also for surface preparation after
complete depainting prior to the complete repainting of an
aircraft. All Technical Order requirements and procedures for
prepaint preparation of metal surfaces other than aluminum
and magnesium, which may be used on aircraft exterior
surfaces, shall be complied with in addition to requirements
of this manual.
3.1.1 Surface Preparation For Painting.
• Refer to Table 3-1 for minimum personal
protective equipment required for all paint
preparation operations.
• Provide adequate ventilation when using sol-
vents. Avoid prolonged breathing of vapors
and avoid skin contact. Use appropriate pro-
tective gloves and eye protection. Contact
Bioenvironmental Engineering to determine
need for respiratory protection.
Surface preparation for painting is the most important re-
quirement for insuring proper adherence and performance of
a paint system. For the purposes this manual, there are two
types of surfaces requiring preparation for painting; bare
unpainted surfaces (metal or composite material) and surfaces
with organic coatings currently applied. In either case, an
exceptionally clean surface is necessary whether painting
over an existing paint system, painting newly fabricated
aircraft or components, or after complete removal of an
existing paint system or to overcoat an existing paint system
must be thoroughly prepared before the re-application of new
organic coatings.
3.1.2 Surface Preparation For Repair or Over Coat-
ing of Damaged Organic Coating. Closely inspect
candidate areas for the extent of damage and maintenance
painting required. If inspection reveals major paint failure or
damage, such as chipped or peeled paint from the center of a
skin panel, the involved skin section should be prepared and
maintenance painted from seam to seam. If only minor
damage is found, i.e., paint chipped or missing from screw/
rivet heads and on outer edges of skin panel(s) the specific
area may be prepared and maintenance painted. Prepare
damaged area(s) as follows:
3.1.2.1 Thoroughly clean the area to be prepared per TO
1-1-691 or using solvent wipe procedures per Paragraph
3.1.4.
• Sanding of finish systems using motor driven
abrasives can generate airborne particles and
toxic dust that can injure personnel and create
a possible dust explosion from paint and
abrasive material dust. Work pieces and mo-
torized equipment shall be properly electri-
cally grounded. When using motor driven
abrasives the minimum required personnel
protective equipment shall be dust/particulate
respirator, goggles/face shield, disposable ni-
trile rubber gloves, and cloth coveralls with
paint sock or hooded Tyvek coveralls and
non-slip rubberized foot coverings. Do not
stand above, below or directly next to other
workers. Avoid being “downwind” from oth-
ers using mechanical sanders. Consult Bioen-
vironmental Engineering Services for respira-
tory and ventilation requirements.
• Do not mount an abrasive on a motor driven
tool having an operational speed higher than
the maximum RPM rating of the abrasive.
This can result in disintegration of the abrasive
and can cause injury to personnel.
3.1.2.2 Feather the edges of damaged coating adjacent to
the peeled section. Use 120 grit or finer abrasive paper or
nylon abrasive matting material Specification A-A-58054
medium grade or finer for sanding. When using the coarser
grit sizes down to 120 use care not to score the metal surfaces.
Sanding to feather-out the damaged coatings may be done by
hand or with the use of either a random orbital tool or
pneumatic drill motor (12,000 RPM max) fitted with a roloc
TO 1-1-8
3-1