Textron Cessna 172R - Page 486

SECTION
9
-
SUPPLEMENTS
SUPPLEMENT
20
-
FAA
APPROVED
CESSNA
MODEL
172R
3.
RECEIVE AUDIO
SELECT BUTTONS
-
Push
button
audio
selection
is
available
for
two
Communications
receivers
(“COM
1",
“COM
2“),
two
Navigation
receivers
(“NAV
1"
and
"NAV
2“),
the
internal Marker
Beacon
receiver
("MKR"),
one
DME,
one
ADF,
one
additional
auxiliary
receiver
("AUX")
and
a
speaker
amplifier
(“SPR").
The
“AUX"
position
could be
used,
for
example,
for
a
second
DME
or
ADF.
When
a
receiver's audio
is
selected,
the
green
annunciator illuminates
at
the
side
of
the button.
Push the button
again
to
deselect the
receiver's
audio. These buttons
are
“latched*
type
switches.
When
one
of
these
buttons
is
pressed,
it
will
stay
in
the
"in“
position
until the
button is
pressed
again
and it
will
be
put
in
the
“out"
position
and
removes
that
receiver
from
the audio. To
provide
additional
feedback
for
button
operation,
activate the
key
"click"
by
pushing
and
holding
both
COM
1
and
COM
2
receiver buttons
for
five
seconds,
and
release.
Repeat
to
defeat
the
dick.
4.
MICROPHONE
SELECTOR SWITCH
(MIC)
-
Used
to
select the
desired
transmitter
for
the
cockpit
microphones.
The
“COM
1“,
“COM
2“,
and
“COM
3"
positions
are
for
transmitting
on
the
Com
1,
Com
2,
and
Com
3
communications
transceivers,
respectively.
When
the mic
selector switch is
in
the
COM
1
position,
both
pilot
and
copilot
will
be
connected
to
the
COM
1
transceiver.
Only
the
person
who
presses
their Push-to-Talk
(PTT)
switch,
will
be heard
over
the
aircraft
radio.
Turning
the
rotary
switch
to
the
COM
2
position
will
place
pilot
and
copilot
on
COM
2.
The
KMA
28
gives
priority
to
the
pilot’s
PTT.
If
the
copilot
is
transmitting,
and
the
pilot
presses
his
PTT,
the
pilot's
microphone
will
be heard
over
the selected
COM
transmitter.
Turning
the
mic selector
counterclockwise
to
COM
3
places
both the
pilot
and
copilot
on
COM
3.
Com
3
receiver audio is
automatically
placed
in
the
headset
(and
speaker
if
selected).
COM
1
and/or
COM
2
receiver
audio
can
be selected
to
monitor those transceivers.
Audio
from
the
selected transceiver is
automatically
heard
in
the
headsets.
This
function
can
be checked
by switching
from
COM
1
to
COM
2
and
watching
the
selected
audio
light
on
the selector
change
from COM
1
to
COM
2.
This
ensures
the
pilot
will
always
hear the audio
from
the
transceiver
he
is
transmitting
on.
When
transmitting,
the
COM
1
or
COM
2
LED
audio selector
will
blink
as a
further
indication
of
the
selected transmitter. When
switching
the mic selector
switch
from
COM
1
to
COM
2,
if
the
COM
1
audio
has
been
selected,
COM
1
audio
will
continue
to
be heard. When
switching
from
COM
1
to
COM
2
if
COM
1
has
NOT
been
selected,
COM
1
audio
will
be switched
off.
Figure
1
.
Bendix/King
KMA
28
Audio
Selector
Panel
(Sheet
2
of
5)
S20-6
Dec
30/00
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