TB 1-1615-351-23
g. Coating Repair. Local damage to the polyurethane coating can be touched up by brushing
additional coating to 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.
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 scrape if
necessary. Remove adhesion promoter with cloth dampened with toluene.
j. Track and Balance Check. Check track and balance of the main and tail rotors per -23 TM.
k. Inspection of Main Rotor Polyurethane 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.
(4) Inspect for inboard and outboard ends of tape segments for disbonding. No more than 0.5
inch-spanwise or chordwise is allowed.
(5) 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 tom.
CAUTION
If damage is discovered and found to be within the above limitations, do not trim
of these damaged areas. Trimming off these damaged areas creates an increasingly
lighter blade and may cause an out of balance condition.
l. Inspection of Main Rotor Agcoat. Wear through to blade surface not allowed.
m. Inspection of Tail 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 more than 0.25 inch
chordwise width for any spanwise length of tape or 0.5 inch cordwise 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 that
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 disbonding on a single tape segment. There is no limit to the
number of disbonds per tape segment providing material is not torn.
Change 3
3-17
