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After
the
solenoid
is de-energized,
the
shuttle
3.
If
the test
equipment
does not indicate
a com-
returns
to the
"dump"
position.
When
the
remaining
plete
circuit,
check
the
circuit
from
the
timer,
to
boot pressure
lowers
to
1
to
1.5 psig,
the
ball poppet
the
solenoid
connector,
to
ground.
opens
to the
vacuum
port,
permitting
the
boots
to
evacuate.
4. Replace
defective
timer
component
(holding
relay
or
time-delay),
if
necessary.
Two small
lines,
pilot
pressure
and
priority
pres-
sure,
plumbed
between
the
valve
assemblies
in
the
5.
Use
an ohmmeter
to
check
the
solenoid
for an
nacelles,
allow operation
of
the
system
on one en-
open
circuit.
If
the
solenoid
circuit
is open,
replace
gine by using pressure
from the
valve
for
the
oper-
the
control
valve.
ative
engine
to
operate
the
shuttle
in
the
opposite
valve.
c.
On Goodrich
control
valves
only,
if
the
solenoid
circuit
is
satisfactory
perform
the
following
check:
Each
control
valve
assembly
incorporates
a
filter
to
remove
oil and any foreign
particles
from
the
1. Remove
the
solenoid
safety
wire
and unscrew
system.
the
solenoid.
CAUTION(
OPERATION
CHECK
Do not lose
the
steel
hex actuator
pin or
a. With both engines
operating
at cruise
rpm,
the
valve
poppet.
momentarily
place
the
deicer
switch
in
the
AUTO-
MATIC position;
the
deicer
boots
should
inflate
for
2. Reattach
the
connector
to the
solenoid,
insert
five
to
eight
seconds,
then
deflate
and reach
a
vac-
the
hex
actuator
pin into
the
solenoid,
and
actuate
uum hold-down
condition.
During
inflation,
check
to
the
deicer
switch.
If
the
pin is not ejected
from
the
see
that
system
pressure
is within
the
green
are on
solenoid,
replace
the control
valve.
the
deicer
system
pressure
gage,
b.
Place
the
deicer
switch
in
the
MANUAL position
Air Leakage
Test
and hold
for
a few seconds;
the
deicer
boots should
inflate
and remain
inflated
while
the
switch
is retained
a.
Cap
the
overboard
port
of
the
control
valve
in
in
the
MANUAL position.
Check
for correct
system
either
the
left or right
nacelle,
pressure.
b.
Connect a
source
of clean
air
to the
inlet port
c.
Release
the
deicer
switch,
permitting
it
to
of
the
capped
control
valve.
A minimum
inlet pres-
return
to the
OFF position;
the
deicer
boots
should
sure
of
18 to
20 psig is required
for
the
test.
deflate
and reach
a
vacuum
hold-down
condition.
c.
Install
a pressure
gage in
the
air line
to
observe
d.
Repeat
Steps
a
through
c with each engine
oper-
system
pressures.
ating individually
at
cruise
rpm.
d.
Apply 18 psig pressure
to the
system
and with a
hand operated
valve,
trap
the
pressure
in
the
deicer
SYSTEM
CHECKOUT
system.
Control
Valves
e.
Observe
the
system
for leakage;
the
leakage
rate
should
not
exceed
a pressure
drop of 4.0 psig
a.
Check
control
valve
operation
as
follows:
per
minute.
1. Turn on
the
battery
master
switch.
f
.
Remove
the test
equipment,
lubricate
all
threads,
and replace
all system
components.
2.
Momentarily
place
the
deicer
system
switch
in
the
AUTOMATIC
position.
Vacuum
Relief
Valve
Adjustment
3.
The control
valve
solenoid
should
be actuated
For
proper
operation
of
the
deicer
system
the
air-
immediately
for seven seconds
as
evidenced
by
an
craft
vacuum
relief
valves
must be adjusted
to
audible
"click"
at
the
beginning and
at
the
end of
the
provide
adequate
vacuum.
See Vacuum
System,
this
cycle.
The
"click" can also
be detected
by placing
manual
if adjustment
is required.
the
hand on
the
solenoid.
b.
If a control
valve
does not function,
proceed
as
COMPONENT
MAINTENANCE
AND REPLACE-
follows:
MENT
1. Unplug
the
electrical
connector
at
the
solenoid.
Air Filters
2.
Attach
a
test
light
or
other
suitable
test
equip-
a. Goodrich Control
Valve Installation.
ment
to
the
connector and
place
the
deicer
switch
in
the
AUTOMATIC
position.
Examine
the
filter discs
after
each
100 hours
of
3-51
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Table of Contents
Troubleshooting
