Some rotor blades may be painted with acrylic lacquer, and MEK can adversely
affect this paint and the subsequent quality of the erosion protection. In this case,
MEK should not be used as a cleaning agent.
(2) Layout and Mask. Layout and mask off main rotor for polyurethane tape application as shown in
(3) Cut Tape. Refer to table 3-15 and cut 8 piec es of 4-inch wide polyurethane tape 36 inches long:
Surface preparation and cleaning are the most important steps to insure proper
(4) Surface Preparation. Scuff the masked off area with 120 grit sandpaper. Only sand in a spanwise direction,
figure 3-1, sheet
of a power polishing sander
is permitted for this procedure.
Do not sand the bare metal skin of helicopter rotor blades. Sanding bare metal
skin 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.
Perform 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 area covered by the
first piece of tape, shown in figure 3-24. Allow to dry at least five minutes, but not more than one hour before applying
tape. Promoter can extend beyond end of tape. Apply promoter in tape length segments to avoid contamination of
coated surface. 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.