f. 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.
g. 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.
h. Polyurethane Tape Removal. Slowly peel back over itself. Scrape tape with plastic scraper, if
necessary. Remove adhesion promoter with cloth dampened with toluene.
i. Track and Balance Check. Check track and balance of main rotor blade per -23 TM.
j. Inspection of Main Rotor Polyurethane Tape.
(1) Inspect 4-inch tape for wear. No more than 0.5 inch wide spanwise or chordwise hole allowed
on trailing edge. No holes allowed on any other surface of tape.
(2) Inspect upper and lower trailing edge of tape for disbonding. No mo re 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.
(3) Inspect for inboard and outboard ends of tape segments for disbonding. No more than 0.5 inch
spanwise or chordwise is allowed.
(4) Inspect for internal disbonding of tape segments. No more than a single disbonding larger than
3.0 inches spanwise and/or 2.0 inches chordwise is allowed. In addition, no more than a total of 6
square inches is allowed for multiple disbonds on a single tape segment. There is no limit to the number
of disbonds per tape segment providing material is not torn.
If damage is discovered and found to be within the above limitations,
do not trim off these damaged areas. Trimming off these damaged areas
creates an increasingly lighter blade and may cause an out of balance
k. Inspection of Main Rotor Agcoat. Wear through to blade surface not allowed.