Cessna 152 - Page 133

CESSNA
MODEL 152
SECTION7
AIRPLANE
&
SYSTEMS
DESCRIPTIONS
provides
the
suction
necessary
to
operate
the
attitude
indicator
and
directional
indicator.
The
system
consists
of
a
vacuum
pump
mounted
on
the
engine,
a
vacuum
relief
valve
and
vacuum
system
air
filter
on
the
aft
side
of
the
firewall
below
the
instrument
panel,
and
instruments
(including
a
suction
gage)
on
the
left
side
of
the
instrument
panel.
ATTITUDE INDICATOR
An
attitude
indicator
is
available
and
gives
a
visual
indication
of
flight
attitude.
Bank
attitude
is
presented
by
a
pointer
at
the
top
of
the
indicator
relative
to
the
bank
scale
which
has
index
marks
at
10°, 20°, 30°, 60°,
and
90°
either
side
of
the
center
mark.
Pitch
and
roll
attitudes
are
presented
by
a
miniature
airplane
in
relation
to
the
horizon
bar.
A
knob
at
the
bottom
of
the
instrument
is
provided
for
in-flight
adjustment
of
the
miniature
airplane
to
the
horizon
bar
for
a
more
accurate
flight
attitude
indication.
DIRECTIONAL INDICATOR
A
directional
indicator
is
available
and
displays
airplane
heading
on
a
compass
ca.rd
in
relation
to
a
fixed
simulated
airplane
image
and
index.
The
directional
indicator
will
precess
slightly
over
a
period
of
time.
Therefore,
the
compass
card
should
be
set
in
accordance
with
the
magnetic
compass
just
prior
to
takeoff,
and
occasionally
re-adjusted
on
extended
flights.
A
knob
on
the
lower
left
edge
of
the
instrument
is
used
to
adjust
the
compass
ca.rd
to
correct
for
any
precession.
SUCTION GAGE
A
suction
gage
is
located
on
the
left
side
of
the
instrument
panel
when
the
airplane
is
equipped
with
a
vacuum
system.
Suction
available
for
operation
of
the
attitude
indicator
and
directional
indicator
is
shown
by
this
gage,
which
is
calibrated
in
inches
of
mercury.
The
desired
suction
range
is
4.5
to
5.4
inches
of
mercury.
A
suction
reading
below
this
range
may
indicate
a
system
malfunction
or
improper
adjustment,
and
in
this
case,
the
indicators
should
not
be
considered
reliable.
STALL
WARNING
SYSTEM
The
airplane
is
equipped
with
a
pneumatic-type
stall
warning
system
consisting
of
an
inlet
in
the
leading
edge
of
the
left
wing,
an
air-operated
horn
near
the
upper
left
comer
of
the
windshield,
and
associated
plumbing.
As
the
airplane
approaches
a
stall,
the
low
pressure
on
the
upper
surface
of
the
wings
moves
forward
around
the
leading
edge
of
the
wings.
This
low
pressure
creates
a
differential
pressure
in
the
stall
warning
system
which
draws
air
through
the
warning
horn,
resulting
in
an
audible
warning
at
5
to
10
knots
above
stall
in
all
flight
conditions.
1
July
1978
7-31