Cessna T188C - Butterfly Valve Disassembly and Reassembly

MODEL
188
& T188
SERIES
SERVICE
MANUAL
19-82.
DESCRIPTION.
An electric
three-way
spray
SHIM
CHART
valve
assembly
is available
for
mounting
between
the
pump.
the
hopper
and
the
nozzles.
The
valve
is con-
SIZE
PART
NO.
THICKNESS
trolled
by a flexible
shaft
and
a knob
in the
cockpit.
This
valve permits
a bypass for pressure
control
and LARGE
1608075-1
005
also provides
recirculation
through the
hopper for a
SMALL
1608075-3
005
more
consistent mixture
of the spray
material
Also LARGE
1608075-2
014
incorporated
into the control
valve is a bleed-back
SMALL
1608075-4
014
valve
to relieve
boom
pressure
after the
control
valve
is
closed
to prevent
nozzle
"drip".
19-83.
REMOVAL
AND
INSTALLATION.
NOTE
NOTE
The
instructions
outlined
in
paragraph
19-86
should
be followed
if Single-Engine
Service
If the
adjustment
screw
is not
disturbed.
Letters
SE78-31
and/or
SE78-59
have
not
suction
adjustment
should
not be
required.
been
complied
with.
To
comply
with
these
Service
Letters,
refer
to paragraphs
19-87
a.
Completely
drain hopper.
and 19-88
b.
Disconnect
plugs
at motor,
remove
sta-strap
and
remove
wiring.
19-86.
BUTTERFLY
VALVE
DISASSEMBLY
AND
c.
Disconnect
hose
coupler
at forward
end
of valve.
REASSEMBLY.
(See
figure
19-29.)
d.
Remove
hose
and
clamps
at aft
end
of
valve.
e.
Remove
bolts
attaching
valve
to adaptor
at gate-
NOTE
box
and remove
gasket
or seal.
f.
Reverse
preceding
steps
for
valve
installation.
The
manual
and
the
electric
valves
contain
identical
parts.
Therefore,
the following
19-84.
DISASSEMBLY.
(BALL
TYPE
VALVES)
procedures
apply
to
both
valves.
(See
figure
19-28
for
valve
disassembly).
a.
Remove
bolts
and washers
from
coupler
adapter
NOTE
(2) and
hose
adapter
(15).
b.
Remove
coupler
adapter
(2),
O-ring
packings
(3)
If adjustment
screw
(21) is
not
disturbed,
and
(5),
and shims
(4).
suction
adjustment
should
not be
required.
c. Remove
hose
adapter
(15),
O-ring
packings
(3)
and
(15),
and
shims
(4).
19-85.
ASSEMBLY.
(BALL
TYPE
VALVES)
(See
figure
19-28.)
CAUTION
a.
Install
ball
(6). packing
(20).
support
assembly
(8)
with
packing
(19).
valve
control
support
(10)
and
Do
not
intermix
total
shim
thickness
from
worm
gear
(9).
end-to-end.
Insert
must
be centered
to
b.
Check
ball (6)
and
seals (3),
(24)
and (26)
fit as
operate
freely.
follows:
1.
Install
adaptor
(1),
seal (3),
adaptor
(22)
d.
Remove
seal-attaching
screws
(14),
existing
seal
and
seal
(24)
less
packings,
bolts
and washers.
(13),
and
retainer
(12).
If existing
seal
does
not
meet
2.
Applying
equal
forces
against
adaptors
(1)
inspection
criterion,
or
is questionable,
discard
old
and
(22),
measuring
gaps
between
adaptors
(1)
and
seals
and
install
new
seals
(13).
This
will
comply
(22) and
valve
body
(5).
with
Single-Engine
Service
Letter
SE78-31.
3.
Install
shims
(4)
and (25)
as required
to a
thickness
of . 002-inch
less
than each
gap
measure-
NOTE
ment.
4.
Install
side
cover
(29)
and
seal
(26).
If seals
are
replaced
per Service
Letter,
5.
During
assembly,
for
measuring
gap
between
follow
instructions
outlined
in the
Service
valve
body
and
two adapters,
set
valve
assembly
up-
Letter.
If
seals
are
not replaced,
proceed
right,
with
hose
adapter
down
on flat
surface
and
as follows.
cam-lock
adapter
up. Place
a 5
or 6 pound
weight
on
top
to give
"equal
forces"
for
seal-to
-ball
seating.
e. Check
to
see
that
butterfly
halves
(11),
seals
(13),
then
measure
gap.
shaft
(8) and
seal
retainer
screws
are
sealed
(Loctite
6.
Install
shims
(27)
as
required
to a
thickness
Sealant
P/N 59231.
) To
ensure
proper
sealing,
close
of
approximately
.002-inch
less
than
the
gap
measure-
butterfly
valve
until
seat
is
contacted.
Tighten
screws
ment.
(14)
1/4
to 1/2
turn
after
seating
to prevent
deforming
c.
Disassemble
components
and
install
packings
(2).
seals.
(23)
and
(28).
d. Assemble
all
components
and install
attaching
NOTE
bolts
and
washers.
The following
procedure
must
be followed
in
assembling
the
spray
valve.
19-61