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2. With
the
right
engine
running
at 2200 RPM,
(CAUTION)
adjust
the
suction
relief
valve
in
the
right
nacelle
to
obtain a
gage reading
of 5
inches
of
mercury.
Release
the
air pressure
slowly
by unrolling
Loosen
the
locknut
and
turn the
adjusting
screw
the
rubber
tubing;
a sudden
release
of
the
clockwise
to
increase
suction or
counterclockwise
air
pressure
may
damage
the
airspeed
to
decrease
suction.
indicator
.
NOTE
INSPECTING
THE PITOT
SYSTEM
HOSE
If a
reading
of 5
inches
of
mercury
has been
obtained
on
one
instrument
and
the
other
does
After
the
pitot system
is checked
for leaks,
inspect
not
agree,
check
the
lines
of
the
one not
the
hose
sections
for
signs
of
deterioration.
Remove
agreeing
for
foreign
matter.
the
pitot mast
to
inspect
the
hose
attaching
to
it and
tip the
instrument
panel
to
inspect
the
hose section
c.
Stop
the engine
and repeat
steps
a.
and
b. with
attaching
to the
airspeed
indicator.
Hoses
with outer
the
opposite
engine
running.
surfaces
checked or cracked,
particularly
at
the
bends
or
connecting
points,
or which have
become
d.
After
both
suction
relief
valves
have been
hard,
should
be
replaced.
Replace
the
defective
individually
adjusted
to
obtain
5
inches
of
mercury,
hose with hose
that
corresponds
to
Military
Speci-
remove
the tape
from
the
central
relief
valve.
fication
MIL-H-5593.
When a
new
hose is installed,
recheck
the
pitot
system
for
leaks
using
the
proce-
dure
described
previously,
e.
Start
both engines
and set
throttles to
obtain
2200 RPM.
Then adjust
the
central
suction
relief
valve
just
forward
of
the
instrument
panel
to
obtain
INSPECTING
THE
STATIC
AIR SYSTEM
a
gage reading
of 5 inches
of mercury.
The static
air system
should
be inspected
at
the
same
time
as
the
pitot system
is inspected,
as
ADJUSTING THE
VACUUM
SYSTEM
(TD-534
thru
follows:
TD-707)
Check
the
rubber
hoses connecting
the
static
air
To
adjust
the
vacuum
system
on
aircraft
serials
TD-
line
to the
instrument
plumbing
and
the
rubber
hose
which
forms
the
static
air
line
drain
(prior
to
TD-
534 Thru
TD-707.
638)
accessible
through the
inspection
opening
in
a. Start only one
engine
and
set
the
throttle to
the
left
side
of
the
baggage
compartment.
Hoses
obtain 2200 rpm.
with
outer surfaces
checked
or cracked,
particu-
larly
at
the
bends
or connecting
points,
or
which
.
have
become
hard,
should
be replaced.
Replace
b.
Adiust
the
appropriate
vacuum
regulator
behind
the
mstrument
panel
to
obtain
a
gage reading
of 4.8
defective
hose
with
hose
meeting
the
specifica-
.
.
to
4.9
inches
of
mercury.
Shut down
the
engine.
tions
described
above
in
the
pitot
system.
Remove
one end of
the
hose which
forms
the
static
c.
Repeat
steps
a.
and
b. with
the
opposite
engine
air line drain
and
permit
the
system
to
drain,
runnmg.
Frequent
draining of the
static
air line is recom-
d. After both vacuum
regulators
have been indi-
mended
when
humidity
is high
or
when heavy
dews
are
experienced.
Also,
the
line
should be drained
vidually
adjusted,
start
both engines
and set
the
each
time the
airplane
is
flown
through
heavy
rain
throttles to
obtain
2200 rpm.
The gage reading
should
then
read between
5.0 and
5.2
inches
of
or washed
down.
mercury.
If
the
reading
is
over
5.25,
or
goes
over
5.25 during maximum
power
operation,
reduce
both
regulators
slightly
to
reduce
the
total
to
within
ADJUSTING
THE
VACUUM
SYSTEM
(Prior
to
limits.
TD-534)
To adjust
the
vacuum
system;
on aircraft
prior
to
TD-534.
PRESSURE
SYSTEM
(TD-708
and after)
a.
Start only
one engine
and set
the throttle to
The pressure
system on
aircraft
serials
TD-708
and
obtain 2200
RPM.
after
provides
air
for
deicer and
instrument
opera-
tion.
Air pressure
is
derived from
two
engine-
b.
Position
the
vacuum selector
valve
to the
driven
dry air pumps.
Air pressure
from
the
pumps
operating
engine and
check
the
vacuum
gage
reading
is
regulated
by a pressure
relief
valve
located
in
for 5 inches
of
mercury.
If
the
gage
does
not indi-
each nacelle.
The
air
is
then
filtered
and directed
cate
5
inches:
to
a
manifold,
which distributes
the
air
to
the
instrument
panel
and deice
system
(if installed).
1.
Tape
the
air
intake
screen on
the
bottom
of
System pressure
is
indicated
by a gage on the
the
central suction
relief
valve.
instrument
panel.
3-29
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Table of Contents
Troubleshooting
