Cessna R182 - Altimeter; Directional Indicator

CESSNA
MODEL
R182
SECTION 7
AIRPLANE
&
SYSTEMS DESCRIPTIONS
(
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-driven
vacuum system
(see
figure 7-10)
provides
the
suction
necessary
to operate the attitude indicator
and directional indica-
tor. 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
The attitude
indicator
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 10o, 2Oo,30o,
60",
and90o
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 fiight attitude
indication.
DIRECTIONAL
INDICATOR
A
directional
indicator displays airplane heading
on a compass card in
relation
to
a fixed
sirnulated 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 card
to
correct
for
any
precession.
SUCTION
GAGE
The suction
gage,located
below the flight instruments, is
calibrated
in
inches of mercury
and indicates suction
a,vailable
for operation of the
attitude and
directional
indicators. 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 indica-
tors should
not
be considered
reliable.
{
(
7-39