The application of edge sealant is particularly important in maintaining
3M 8663 polyurethane protective tape integrity when applied at butt joints
of adjacent PPT.
(20) Assemble a nozzle and a cartridge on the 3M EPX applicator. Squirt out a small quantity to
insure that a uniform mix is attained. Using the nozzle, apply a 1/8 inch bead around the perimeter of
the 3M 8663 polyurethane protective tape panel. Allow this to set up for about 10 minutes, before
removing the tape. The sealant should still be liquid.
For best results: To allow the edge of the sealant bead to blend with
the 3M 8663 polyurethane protective tape and paint. Higher tempera-
tures will require less time for the sealant to gel. Lower temperatures
will require more time for the sealant to gel, so some adjustment in
the 10 minutes may be necessary. The objective is to get the masking
tape off while the bead of sealant is still flowable, to let it blend without
a sharp edge.
(21) Inspect the edge seal application for any small air bubbles and if any are found, they can be
relieved by pricking with a hypodermic needle.
(22) The rotor blade is ready to return to service after the sealant is well cured, and the 3M 8663
polyurethane protective tape has had time to reach a acceptable level of adhesion. This is achieved
after 24 hours at 72 degrees.
c. Blade Installation. If necessary, install main rotor blades per -23 TM.
d. Polyurethane Curing. After polyurethane application, allow 24 hours curing time.
e. Tape Repair. Replace the entire damaged piece of tape. Remove with a plastic scraper. Replace
per the installation instructions.
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.
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
(2) Clean the damaged tape area with a clean piece of cheesecloth dampened with Isopropyl
(3) Wipe the damaged tape area completely dry with a clean, dry piece of cheesecloth.