Cessna 172P - Vertícal Speed Indicator; Altimeter; Directional Indicator; Suction Gage

SECTTON
7
AIRPLANE
&
SYSTEMS
DESCN,IPTIONS
CESSNA
MODEL 17¿P
VERTICAL
SPEED
INDICATOR
The
vertica
s
in
feet per
minute
d
es
lesulting
frorn
s
ALTIMETER
Airplane altitude is depicted
by a
barometric
type
altimeter.
A knob
near
the lower left
portion
of the indicator provides
adjustment
of
the
instrument's
barometric
scale to
the current
altimeter
setting.
VACUUM
SYSTEM AND INSTRUMENTS
An engine-äriven
vacuum
system
(see
figure
Z-g)
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 va,cuum system
air
filter
on
the aft
side of the
firewall
böIow the
instrument
panel,
and instruments
(including
a suction
gage)
on the left
side of the
instrument
panel.
ATTITUDE
INDICATOR
The
attitude indicator
gives
a visual
indication
of ftight
attitude.
Bank
¿r,ttitude
is
presented
by
a
pointer
at the top
of the
indicator
relative
to the
bank
scale
which has index
marks
at 10o, ZO",
B0o,
60o, and
g0o
either
side of
the
center
mark. Pitch
and roll
attitudes
are
presented
by
a
miniature
airplane
superimposed
over
a symbolic
horizon
area
divided
into
two
sections
by a white
horizon
bar. The
upper
"blue
sky"
area
and
the lower
"ground"
area have
arbitrary
pitch
reference
lines
useful
forpitch
attitude
contlol.
A
knob at
the bottom
of the
instrument
is
provided
for
in-flight
adjirstment
of the miniature
airplane
to the
horizon
bãr for
a more
accurate
flight
attitude indication.
DIRECTIONAL
INDICATOR
A
directional
indicator
displays
airplane
heading
on
a
compass
cerd
in
relation to
a
fixed
simulated
airplane
image
and
index.
The indicator
wiII
piecess
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
card to
correct
for
precession.
7-34
30
May
1980