Technical data

is removed, it is a lacquer or alkyd enamel coating. If
it is not removed, or very little is removed, it is a
polyurethane or an epoxy coating.
(2) For polyurethane and epoxy coatings, scrape off the
topcoat from a small area down to the primer coating
with a knife blade or razor blade. If the primer is
rubbery and a tan-gray color, it is a polysulfide
primer. If the primer is hard and either a yellow, light
brown, or dark green (olive drab) color, it is either an
epoxy or a polyurethane primer.
d. As a last step, study the removal operation to be
performed and determine the most logical and efficient
process for the job. If confined areas are involved, they
shall be protected during a general overall removal
operation, and shall be stripped using the special proce-
dures in this chapter for these areas. If fiberglass, kevlar,
or other composites are involved, they shall be stripped
using the special procedures outlined later in this tech-
nical order. For extensive removal operations, such as
removal of the entire exterior finish system on aircraft
and large pieces of equipment, a detailed sequential
step-by-step process specification confirming to all of
the requirements in this chapter shall be prepared and
followed. All personnel involved with finish system
removal shall be trained in and thoroughly familiar with
all requirements of this chapter.
2.3 PREPARATION FOR PAINT REMOVAL.
All aircraft will be de-energized per AFOSH STD 91-17,
support equipment or components must be properly prepared
for paint removal operations. Additionally, it is essential that
all facilities and equipment for paint removal operations meet
the safety and environmental requirements for the processes
to be employed. Once the process for paint removal has been
selected, use the following preparation requirements to pre-
pare the aircraft, support equipment or component.
a. Inspect all surfaces to be stripped for grease, oil, and
dirt. These materials act as a barrier between the finish
system and the chemical or abrasive removers and will
contaminate recoverable air-driven abrasives. This can
cause excessive man-hour expenditures, longer flow
times, and additional waste generation during removal
operations. Small amounts of these contaminants do not
cause a problem; but if surfaces are exceptionally dirty,
oily, or greasy, they shall be washed in accordance with
TO 1-1-691 prior to removal operations. After washing,
surfaces shall be either wiped dry, or sufficient time shall
be allowed for them to air dry prior to removal opera-
tions. Small areas or components may be cleaned using
a solvent wipe per Chapter 3 of this manual.
b. Position the aircraft, equipment, or component from
which the finish system is to be removed in a covered
facility. If chemical removal methods are to be used, this
facility shall be capable of maintaining the ambient air
temperature within the range of 50° F to 100° F. In
addition, the item from which the finish system is to be
chemically removed shall be placed in the facility for a
length of time sufficient to allow its surface temperature
to reach 50° F to 90° F prior to application of the
remover. While chemical removal can be accomplished
within the ambient air temperature range of 50° F to
100° F, severe difficulties will be encountered outside a
temperature range of 70° F to 90° F. Below 70° F,
chemical removal is very inefficient because the action
of chemical removers is extremely slow; so the flow
time, man-hours, and amount of remover required for
chemical removal operations will be increased signifi-
cantly. Above 90° F, the solvents in chemical removers
evaporate so rapidly that removal efficiency is severely
reduced and its drying on the surface makes it severely
difficult to clean the finish system and remover residue
from surfaces. This too will cause a significant increase
in flow time, man-hours, and amount of remover re-
quired for chemical removal operations.
c. Protect all special areas, equipment, and materials by
masking or other specified protective devices. For
chemical removal operations, masking shall be accom-
plished with MIL-PRF-131, Class 1, barrier material
and MIL-T-23397/SAE AMS-T-23397, Type II, (72-
hour protection) aluminum backed, pressure sensitive
tape. For extensive stripping operations such as depot
level complete exterior finish system removal from
aircraft and large pieces of equipment, use only 3M Co.
Part Number (PN) 425 tape (3M Co. Address: Minne-
sota Mining and Manufacturing, Industrial Tape Div.,
3M Center, St. Paul MN 55101). This is the only tape
which will provide adequate protection for the extended
time period involved with this type of operation. The
engineering support activity for this technical order
evaluates and approves tapes for this source control
listing using the latest issue of MIL-T-23397/SAE
AMS-T-23397. Chemical stripper CeeBee R-256 is used
as the testing agent for stripper resistance. Make sure
that the plastic coated side of the MIL-PRF-131, Class
1, barrier material is toward the surface being protected
or the plastic will be deteriorated by chemical removers.
NOTE
Specific 3M Co. PN 425 Tape NSNs can be found
using the following part number “425 + * ⁄ * +
in” in Fed Log Supply System.
TO 1-1-8
2-2