(1) Cleaning. Clean area shown in figure 3-25 with cheesecloth or machinery towel dampened with MEK,
isopropyl alcohol, or denatured alcohol.
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 figure 3-25.
(3) Cut Tape. Refer to table 3-18 and cut tape per below.
Cut 42 pieces of 8-inch wide polyurethane tape 36 inches long.
Cut 36 pieces of 2-inch wide polyurethane tape 36 inches long.
Cut 6 pieces of 2-inch wide polyurethane tape 24 inches long.
Surface preparation and cleaning are the most important steps to insure proper
(4) Surface Preparation. Remove paint from blade, figure 3-25, with MEK or sandpaper. Scuff the masked off
area with 120 grit sandpaper. Only sand in a spanwise direction, figure 3-1, sheet 1. Use of power polishing sander is
permitted for this procedure.
Do not sand the bare metal skin on helicopter rotor blades. Sanding bare metal
skin on helicopter rotor blades reduces the structural integrity and fatigue life of
(5) Cleaning. Wipe the masked area several times with cheesecloth or machinery tow el dampened with
isopropyl alcohol or denatured alcohol, then wipe once again with a clean, dry cloth.
(6) Application of Adhesive Promoter. Apply a thin coat No. 86 adhesive promoter to the area covered by the first
piece of tape, shown in figure 3-26. 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