Cessna T188C - Page 401

MODEL
188
& T188
SERIES
SERVICE
MANUAL
back as required
to
expose the
damaged
area. Pre-
b.
Establish
and mark
each delaminated
area,
then
vent damage
to the wing
walk
material
and protect
the
mark a
smooth
contour
which encompasses
all
dam-
adhesive
backing
from sanding
dust
and other
foreign
age.
matter. Damage to the catwalk is divided into the
following
categories:
NOTE
CLASS 1: Cracks
or punctures
penetrating
outer skin
An easy
and reliable way
to establish
de-
only,
without apparent
delamination
between
skin and
laminated
areas is to tap
all suspected
honeycomb core
or damage
to core.
areas with
a heavy coin,
listening to
the
sound made by the coin. A solid sound
CLASS II: Cracks,
punctures,
or locally
crushed
results
where areas are
not delaminated,
areas,
accompanied
by delamination
between
outer
but a lighter
sound is readily
detected in
skin and honeycomb
core,
but without
delamination
delaminated
areas.
between core and inner skin.
c. Remove outer skin in area marked. Scribe the
CLASS II: Class
II damage accompanied by damage
marked area smoothly,
without sharp corners, then
to honeycomb
core,
with or without
delamination
cut through
the skin by
repeatedly dragging
the end
between
core and
inner skin, but
without damage
to tooth
of a hacksaw blade
along the scribed
line. Once
inner
skin.
an edge
of the skin in the
damaged area
has been lift-
ed, the
skin may then
be removed by
peeling it back
CLASS IV:
Puncture of
total composite,
accompanied
to break the
bond with the
honeycomb, thus
leaving
by delamination
between honeycomb
and
both skins.
the honeycomb
undamaged.
d. Remove surface gloss for two inches beyond
NOTE
opening
by sanding
with a coarse
abrasive.
e. Prepare two pieces of glass-fiber cloth (type
A laminating kit (SK188-1),
a filler kit HG63
or equivalent), one to fit
the open area and the
(SK188-2),
and
a sealer
kit (SK188-3)
other to
fit two inches
beyond
the open
area.
Pre-
are available
from the
Cessna Supply
pare one additional
piece of
cloth (type 128
or equiv-
Division.
Two types
of glass-fiber
alent) also
to fit two inches
beyond the
open area.
cloth are
included in the
laminating.kit.
This is the
cloth to be applied
next to the
wing walk.
Type HG63
is a coarser,
thicker
cloth
f.
Mix the
filler material
according
to directions
than
type 128. Type
HG63 is used for
furnished.
all laminations
except the final
one, for
g.
Fill all exposed
honeycomb,
flush with the
top
which type
128 is
used. The
sealer
kit
of the core,
with this
putty-like
mixture.
is the same
adhesive
contained
in the
h.
Mix the
adhesive
according
to directions
fur-
laminating
kit,
but is packaged
separately.
nished.
i. Brush
a thin film
of adhesive
over the sanded
REPAIR
OF CLASS
I DAMAGE.
The purpose of
re- area
and a relatively
wet coat over
the honeycomb
pairing Class
I damage
is
to seal the
catwalk
to pre-
area.
vent
deterioration
from
moisture.
It is assumed
that
j.
Place the
piece of
glass-fiber
cloth that
was
structural integrity
is not involved.
pre-cut to the size
of the opening
in position,
then
a.
Thoroughly clean
the area with
acetone, ketone,
work
additional adhesive
into the fabric
to impreg-
or other similar
solvent that leaves
no residue.
nate
it completely.
Apply the second
and third pieces
b. Remove
surface gloss
in damaged area,
and for
of pre-cut fabric
to overlap
the open area two
inches,
at least one
inch by sanding
with a coarse
abrasive,
using same laminating
technique.
Use sufficient
ad-
c. Prepare
a piece
of glass-fiber
cloth (type 128
or hesive
to assure
a resin-r.ch
surface.
equivalent)
to
fit one inch
beyond the
damaged
area.
k.
Leave repaired
area
exposed until
adhesive
is
d.
Mix the
adhesive
according
to directions
fur-
no
longer tacky
(about
four hours),
then
smooth
nished.
edges
if necessary.
Reinstall
wing walk.
e. Work some
of the adhesive
into the crack
or
1. Allow repair
to cure a minimum
of 12 hours
at
puncture,
and brush
a thin
film over
the sanded
area,
70F, or
four hours
at 130F.
Proportionally
longer
after
making
sure it is
free from
sanding dust.
curing
time
is required
in cooler
temperature.
f.
Place the pre-cut
cloth in
position, then
work
additional
adhesive
into the fabric
to impregnate
it
REPAIR
OF CLASS III
DAMAGE.
completely
and seal
the damaged
area. Use sufficient
adhesive
to assure a
resin-rich
surface.
a.
Thoroughly
clean
the area with
acetone,
ketone
g. Leave
repaired
area exposed
until
adhesive
is
or other
similar
solvent that
leaves no
residue.
no longer tacky
(about four hours),
then smooth
edges
b. Carefully remove
outer skin.
Also determine
if necessary.
Reinstall wing walk.
the extent
of delamination (if any) between
undamaged
h. Allow repair
to cure a minimum
of 12 hours
at honeycomb
core
and inner skin
by careful probing,
70F,
or four hours
at 130F. Proportionally
longer
since
the outer skin
must also be removed
to repair
curing
time
is required
in cooler
temperature,
these
areas. Remove
any
damaged
honeycomb
core.
c. If any delamination
between
core and
inner skin
REPAIR
OF
CLASS II
DAMAGE.
was
found, mix
the adhesive
according
to directions
a. Thoroughly
clean
the area
with acetone,
ketone,
furnished,
then apply
this adhesive
by working
it
or
other similar
solvent
that leaves
no residue.
down
through the
honeycomb
core.
Use sufficient
Revision 1 17-39