TB 1-1615-351-23
e. Polyurethane Curing. After polyurethane application, allow 24 hours curing time.
f. Tape Repair. Replace the entire damaged piece of tape. Remove with a plastic scraper. Replace
per the installation instructions.
NOTE
TASK L-100 polyurethane paint may be utilized to repair damaged
areas of 3M 8663 polyurethane tape. The damaged tape areas must
not be larger than three inches in diameter. No more than a single
damaged area may be repaired per each thirty-six inch length of tape.
NOTE
All TASK L-100 polyurethane paint and 3M 8663 polyurethane tape
Applications to the aircraft must be maintained in accordance with
Technical Bulletin 1-1615-351-23.
(1) Scuff sand the damaged area with 80 grit sand paper to remove any dirt and debonded edges.
(2) Clean the damaged tape area with a clean piece of cheesecloth dampened with Isopropyl
Alcohol.
(3) Wipe the damaged tape area completely dry with a clean, dry piece of cheesecloth.
(4) Mix and apply TASK L-100 POLYURETHANE PAINT to the damaged tape area per the
instructions in TB 1-1615-351-23 until the damage is repaired.
(5) Allow the TASK L-100 polyurethane paint application to cure six hours before operating the
rotor blades.
g. Coating Repair. Local damage to the polyurethane coating can be touched up by brushing
additional coating to the damaged area. Carefully remove the disbonded material. Scuff the damaged
area with 120 grit sandpaper. Wipe clean with MEK. Prime the area with AGC 1201-7 primer if the
blade surface is exposed. Coat the damaged area with sufficient coats of polyurethane coating to match
the thickness of adjacent areas. Application of TASK L-100 polyurethane paint to repair minor damage
on agcoat material is authorized for this procedure.
h. Polyurethane Coating Removal. Saturate coating surface with MEK and scrape coating off with a
plastic scraper while soft. Make a final surface wipe with cloth dampened with MEK.
i. Polyurethane Tape Removal. Slowly peel back over itself. Scrape tape with plastic scraper, if
necessary. Remove adhesion promoter with cloth dampened with toluene.
j. Track and Balance Check. Check track and balance of main and tail rotors per -23 TM.
k. Inspection of Main Rotor Polyuretane Tape.
(1) Inspect 2-inch tape for wear. No holes allowed.
(2) Inspect 8-inch tape for wear. No more than 1.0 inch-width hole in any spanwise or chordwise
direction allowed on upper or lower side of blade.
(3) Inspect upper and lower trailing edge of tape for disbonding. No more than 0.25 inch
chordwise width for any spanwise length of tape or 0.5 inch chordwise width for 6 inches spanwise
length along a single piece of tape is allowed.
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