TOMARK, s.r.o.
Airplane Maintenance Manual
Chapter 51 Standard Practices Structure
Page 162 Issue: 28.FEB 2017
repair coats is not a compact surface of basic material but mostly al
coats of surface protection (after sanding), of which not all are
suitable for (in ageing stage) for good adhesion of paint coats.
Therefore we recommend to carry out such repairs by a verified
system.
Before repairing it is necessary to differentiate the type of the existing
topcoat, single coat and two-coat (with the top coat). For repair it is
necessary to follow the used type of color. It is suitable to choose the
delimited area (e.g. connection of sheets, wing edge) for the scope of
the place, which is being repaired transition, is then better blended. In
the case that it is not possible to choose the area in this way, it is
necessary to take into consideration the higher difficulty of the
procedure as for the uniformity of shade and elaboration of coat
transition.
Sanding
For good adhesion of the repair coats it is necessary to carry out
sanding of the old paint coat at least up to such depth as the depth of
damage. Ground area must be larger from 51 to 102 mm (2 to 4 in)
than damaged area. With two-coat type of the topcoat it is necessary
to add at least 51 mm (2 in) for the run-out of the top coat.
DANGER Explosion hazard due to abrasive dust.
▶ Remove adhesive and dope only in explosion proof rooms with
exhaustion device.
WARNING Poisoning hazard due to abrasive dust.
▶ Wear externally ventilated protective clothing, protective goggles,
chemical resistant gloves and respiratory mask when removing
adhesive and dope.
▶ Carry out sanding with sander equipped with the suction from the
area of sanding or by manual sanding under water.
NOTICE Risk of destroying the protective anodized layer.
▶ Never sand or roughen anodized structures.
▶ Start sanding with abrasive having grain size of max. 160 and finish
with grain size of 400.
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