Technical data

• Plastic media blasting (PMB) may be used on
composite materials in accordance with pro-
cedures in Paragraph 2.11, providing its use
has been approved by the specific aircraft’s
SPD. In all cases, use PMB to remove only the
topcoat from composite surfaces. The under-
lying primer must be used as a “flag” to signal
the PMB operator that the topcoat has been
removed. When the primer begins to show
during the stripping operation as the topcoat is
slowly removed, the PMB blast should be
directed elsewhere on the surface being
stripped. This technique is essential to avoid
damaging the composite material.
• When using mechanical methods, abrasive
blast media and pieces of broken brushes and
discs can escape from the work area. These
methods shall not be used in areas under
conditions that allow escaped particles to enter
into and damage or contaminate any system,
engine, or other component. Barriers shall be
erected around the work area and masking of
the surrounding area and masking or plugging
of all holes leading to the interior of systems
and equipment shall be accomplished to pre-
vent damage and contamination of systems
and equipment by dust, abrasive blast media,
and pieces of broken brushes and discs. The
system specific aircraft corrosion manual (-23)
or the specific equipment manual shall be
consulted for proper masking requirements.
Mechanical removal methods include the use of hand-held
wire brushes, bonded abrasive papers or cloths, and abrasive
mats; motor-driven wire brushes, bonded abrasive paper or
cloth discs, and abrasive mat discs and flap brushes; and
abrasive blasting. Mechanical removal is recommended when
use of chemical removers is impractical due to structural
complexities and/or rinsing difficulties in an area being
worked and/or local environmental restrictions. While these
methods are very effective for finish system removal, they can
cause severe damage to structure and equipment in a very
short time if improperly used. Consult with weapons system
specific TOs prior to performing work in fracture critical/
no-work areas.
2.10 MECHANICAL REMOVAL METHODS OTHER
THAN PLASTIC MEDIA OR MEDIUM PRESSURE WA-
TER BLASTING FOR METAL SUBSTRATES.
Protective clothing worn during abrasive blasting
operations shall remain in the work area and shall
not be taken home for cleaning.
For any and all mechanical finish system removal operations,
approval for the operation shall be obtained from the respon-
sible ALC as directed in Paragraph 2.9. The area involved in
the operation shall be thoroughly cleaned to remove all oil,
grease, and hydraulic fluid per TO 1-1-691. Masking shall be
accomplished per instruction in Paragraph 2.3 step c and the
applicable system or equipment specific manual prior to
starting the operation. Precautions listed in the cautions and
warnings in this manual, the applicable system or equipment
specific manual, and TO 1-1-691 shall be strictly followed.
Mechanical removal methods consist of hand abrasive or
motor-driven abrasive removal of organic coatings from
various substrate materials and abrasive blasting.
2.10.1 Abrasive Blasting. Iron and Steel Alloys (Other
than Stainless Steel) may be abrasive blasted with aluminum
oxide grit, steel grit, or sand at a maximum air pressure of 40
PSI for a pressure type machine to remove paint. This is very
effective on low-carbon steels and iron as it also removes
rust/corrosion leaving a bright metal surface. Use TO 1-1-691
as control for this type of abrasive blasting, and never use on
steel less than 0.0625 inches thick.
2.10.2 Hand or Motor-Driven Abrasive Removal.
These methods for mechanical removal of a finish system are
basically the same for all substrates. The primary difference is
the type of abrasives used, which vary depending on the
TO 1-1-8
Change 1 2-13