Cessna 188 Series Service Manual 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