CHAPTER 51
PAGE 27
PAGE DATE: 7. July 2010
MAINTENANCE MANUAL EXTRA 300LT
The damaged area of the inner laminate has to be taken out as
well. Make sure not to increase the disbond area when
preparing the hole. Preferably use a hand held milling ma-
chine. In case of cutting with a saw, the pulsation stress may
peel of the inner laminate (secondary damage). If the extent
of the disbonded area on the inner laminate exceeds the
prepared cut out, increase the cut out of material and upper
laminate.
Prepare a scarfed overlap of laminate around the circular cut
out. Overlap lenght of inner laminate should not be less than
20 mm.
I M P O R T A N T Overlap lenght of the upper laminate should not be less
than 1/50; (ratio: laminate thickness / overlap lenght).
Prepare a replacement block of core material (foam or
honeycomb) with equivalent diameter and thickness. Cut it
to fit snuggly in the trimmed hole. In case of foam core, coat
one side with a mixture of resin and microballoons (ratio
100:15). Apply prelaminated fabric layers required for the
inner laminate on this side of the core filler block. Ensure
correct style and direction of fabric. After precuring the
laminate at elevated room temperature (30°C), scarf the
overlap and sand the upper overlapping core material down,
up to the surrounding core material.
Subsequently clean the repair area thoroughly as follows:
1 Remove the sanding dust with a pneumatic vacuum
cleaner.
2 Clean the scarfed overlaps with carbon-tetrachloride or
acetone in case dirt or grease was introduced during the
preparation.
W A R N I N G Carbon-tetracloride or Acetone used for cleaning re-
pair areas are flamable liquids and should be used with
proper ventilation and safety equipment.
I M P O R T A N T Repair area must be free of dirt and grease.
Wet all surfaces of the backing plate and the scarfed area with
resin mixture. Lay on prelaminated fabric layer in accordance
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