Cessna 172N - Avionics and Audio Systems

SECTION
7
AIRPLANE & SYSTEMS
DESCRIPTIONS
CESSNA
MODEL
172N
The
stall warning
system
should
be
checked
during
the
preflight
in-
spection
by
placing
a clean
handkerchief
over
the vent
opening
and
apply-
ing suction. A sound
from the
warning
horn
will
confirm
that
the system
is operative.
AVIONICS
SUPPOR,T
EQUIPMENT
The
airplane
may,
at
the
ownerts
discretion,
be
equipped
with
vari-
ous
types
oiavionics
zupport
equipment
such
as an
audio
control
panel,
micropnone-headset,
and
static
dischargers.
The
following
paragraphs
discuss
these items.
AUDIO
CONTROL
PANEL
Operation
of ra.dio
equipment
is
covered
in Section
9
of this
handbook.
when one
or more
radios are
installed,
a transmitter,/audio
switching
sys-
tem is
provided
(see
figure
?-10).
The
operation
of
this
switching
system
is described
in the
following
paragraphs.
TRANSftlITTER,
SETECTOR
SWIICH
A rotary
type
transmitter selector
switch,
labeled
XMTR
SEL,
is
provided
to
connect
the microphone
to the
transmitter
the
pilot
desires
lo
use.
To
select
a transmitter,
rotate
the
switch
to the number
corres-
ponding
to that transmitter.
The numbers
1, 2 and
3
above
the switch
cor-
respond
to the top, second
and third
transceivers
in
the
avionics
stack.
An audio
amplifier
is
required
for
speaker
operation,
and
is
automati-
cally selected,
along with
the
transmitter,
by
the
transmitter
selector
switch.
As
an
example,
if
the
number
1
transmitter
is selected,
the audio
amplifier
in the associated NAV/COM
receiver
is
also selected,
and func-
tions as
the amplifier
for
ALL
speaker
audio. In
the
event
the
audio am-
plifier
in
use fails,
as
evidenced
by loss
of all speaker
audio,
select
another
transmitter.
This
should
re-establish
speaker
audio.
Headset
audio is not
affected by
audio amplifier
operation.
AUTOfiTATIC AUDIO
SELECTOR
SIVIICH
A
toggle
switch,
labeled
AUTO, can
be
used
to
automatically
match
the
apprdfriate
NAV
/COV|
receiver
audio
to
the
transmitter
being select-
ed.
To
utilize this
automatic
feature,
leave
all
NAV/COM
receiver
switches
in the
OFF
(center) position, and
place
the
AUTO
selector
switch
in either
the
SPEAKER
or
pllOttg
position,
as
desired.
Once
the
AUTO
selector
switch
is
positioned,
the
pilot
may
then
select
any
transmitter
7 -34