TB 1-1615-351-23
(5) Remove the liner from the sheet of PPT. Liberally spray the adhesive side with "wetting
solution" that was prepared in step #4 above. Also spray the surface of the part to which the PPT is to
be applied.
(6) Carefully position the PPT on the part. Use a plastic squeegee, starting at the middle of the
sheet, and remove the wetting solution from beneath the PPT sheet, by using long overlapping strokes.
If you should trap an air bubble, lift an edge to allow the bubble to be removed. When the edge is lifted,
respray with more "wetting solution" to insure that no air is trapped under the PPT. Use a clean rag to
mop up the excess water solution at the edges to prevent the water solution from "wicking" back under
the tape.
(7) Inspect the installation for lack or air or water bubbles. It is permissible to remove a few small
"blisters" by piercing them with a hypodermic needle, and pressing on the bubble to exclude the
air/water.
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 an 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 so. 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 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 segment. 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.
CAUTION
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.
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