j. Applying Polyurethane Coating to Tip Cap. Tail Rotor.
Reference WARNINGS, b, above.
(1) Cleaning. Clean area on blade to be covered 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) Scuff area on tip cap to be covered by coating using abrasive paper. Clean surface using cheesecloth or
machinery towel dampened with isopropyl or denatured alcohol, then wipe once again with a clean, dry cloth.
(3) Cut excess polyurethane tape in 1-inch-wide strips. Use to mask area not being coated. Make sure to use 2
layers of tape on masked area.
Use equal amounts of primer and coating on all blades to minimize balance
adjustments to tail rotor.
(4) To apply polyuret hane coating to tail rotor tip cap do this:
(a) Primer may be brushed on or sprayed on. If brushed on using paint brush, no thinning is required. If
sprayed on, primer must be thinned to 2 part methyl ethyl ketone. Mix primer, part A and part B in equal parts. Apply to
area to be coated. Allow 1-hour drying time at 70 F (21C) or above. Do not handle primed surface. If surface is
contaminated, lightly wipe using cleaning cloth, moistened with alcohol.
Brushed coats tend to result in 0.002-.003-inch thickness.
Sprayed coats tend to result in 0.0007-.001-inch thickness.