TB 1-1615-351-23
CAUTION
Do not puncture bubbles after the adhesive has dried.
(7) Polyurethane Tape Preparation. Peel back one of the center (1 inch wide) backing strips from
the 4 inch wide tape approximately 3 inches as shown in figure 3-1, sheet 3 for the 8" wide tape.
(8) Tape Alignment. Align the tape in the position shown in figure 3-24 before pressing to blade.
(9) Tape Application. When the tape is in proper position, press the exposed portion on the blade
as close to the leading edge as possible. Press down on the tape, working toward the trailing edge to
prevent trapping air bubbles. See figure 3-1, sheet 4. Peel backing strip back while keeping tape aligned
and pressing down toward the trailing edge. Remove the backing strips one at a time, working toward
the trailing edge. See figure 3-1, sheet 5. Thoroughly press down tape. Any bubbles encountered
during the application process may be removed by continuous squeegee stroking towards the edge of
tape or by puncturing the bubbles with a needle and applying pressure to the wet adhesive.
CAUTION
Do not puncture bubbles after the adhesive has dried.
(10) Polyurethane Tape Application. Apply inboard piece of tape with No. 86 promoter as with the
first piece, figure 3-24. Remove masking tape.
NOTE
Repeat Steps (6) through (10) for each blade.
NOTE
The structure to which the polyurethane protective tape, 3M 8663, is
to be applied should be in recent overhaul or new condition. This
means that repairs have been made and the part has been primed and
painted in accordance with the appropriate technical directive for that
part.
NOTE
The rotor blade must be smooth. Any dirt inclusions or paint roughness
must be sanded off the surface using 400 grit sandpaper. Simply, the sur-
face should be at least as smooth as you can get it by sanding with 400
grit sandpaper.
(11) Clean the surface by rinsing with isopropyl alcohol and wiping dry with clean untreated paper towels
or rags.
(12) Using a small clean rag, apply a thin coat of #86A adhesion promoter to the entire area of the rotor
blade that is to be covered with 3M 8663 PPT film. Let the 86A dry 15 minutes, prior to application of 3M
8663 PPT film.
(13) Cut a sheet of 8663 polyurethane protective tape (PPT) to the size of the area to be covered
leaving a margin of 1/8 inch around the perimeter. This margin will later be used for application of the edge
sealant around the perimeter of the PPT sheet.
