TB 1-1615-351-23
(4) Surface Preparation. Scuff the masked off area with 120 grit sandpaper. Only sand in a
spanwise direction, figure 3-1, sheet 1. Use of a power sander is permitted for this procedure.
CAUTION
Do not sand the bare metal skin of helicopter rotor blades. Sanding
bare metal skin of helicopter rotor blades reduces the structural
integrity and fatigue life of the blade.
(5) Cleaning. Wipe the masked area several times with cheesecloth or machinery towel
dampened with isopropyl alcohol or denatured alcohol, then wipe once again with a clean, dry cloth.
NOTE
Perform procedural Steps (6) through (10) for one blade at a time.
(6) Application of Adhesive Promoter. Apply a thin coat of No. 86 adhesive promoter to the
masked area. Allow to dry as least five minutes, but not more than one hour before applying tape.
Promoter can extend beyond ends of tape.
(7) Polyurethane Tape Preparation. Peel back one of the center (1 inch wide) backing strips from
the 4" wide tape approximately 3 inches a shown in figure 3-1, sheet 3.
(8) Tape Alignment. Align the tape in the position shown in figure 3-16 before pressing to blade.
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.
(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) Masking Tape Removal. Remove masking tape.
NOTE
Repeat Steps (6) to (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.
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