h. Polyurethane Coating Removal. Saturate coating surface with MEK and scrape costing 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 self.
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 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 4-inch tape for wear. No more than 0.5 inch wide spanwise or chordwise hole allowed on trailing
edge. No holes Slowed on any other surface of tape.
(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 disbanding. 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 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 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.