Extra 300LX, Maintenance Manual

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CHAPTER 51
PAGE 23 PAGE DATE: 1. March 2011
MAINTENANCE MANUAL EXTRA 330LX
The number of layers required to restore the stability in the
damaged area can be taken from the layer sequence/place-
ment plan (refer to the respective chapters).
It is necessary to know the number and direction of layers in
the damaged area, in order to be able to replace them with the
original number. In all cases, the thickness of the laminate
has to be measured with a vernier calliper for the exact
determination of the laminate thickness.
One technique to learn about the number of layers is to burn
a small piece taken from the damaged area. The resin will
burn off, leaving the glass and/or carbon fabric to be in-
spected for the number of layers and the type of fabric.
Creating a scarfed overlap takes time. Sand away as much of
the old material, so that the new fabric patches do not project
beyond the contour.
In order to shorten the curing time, a heater can be used to
increase the ambient temperature.
N O T I C E Too high temperatures will cause large air bubbles in
the laminate. Local overtemperature can be prevented
by using a foil tent which leads the hot air stream.
The curing cycle must be maintained as stated. Use a ther-
mometer to monitor the temperature.
I M P O R T A N T After repair of control surfaces, check for proper bal-
ance (refer to chapter 27, Flight Controls).
It is recommended to prepare test specimens at the same
time as the actual repair is accomplished. These can then be
subject to a material test to establish the quality of the
laminate in the repaired part. To make this determination
valid, the specimens must be assembled with the same style
of fabric and resin mixture. Subsequently, the specimens
must be subject to the curing pressures, temperatures and
times identical with those in the actual repair.