Cessna 172P - Page 159

CESSNA
MODEL 172P
SECTION
7
AIRPLANE & SYSTEMS
DESCRIPTIONS
SUCT¡ON GAGE
The
suction
gage,
located
on
the left side of
the instrument
panol,
is
calibrated in inches
of mercury
and
indicates suctiou
available
for
operation
of the attitude and directional
indicators.
The deslred
suction
ra,nge is 4.õ
to
5.4 inches
of
mercury. A suction
reading
out of
this
range
may indicate a system malfunotion
or improper
adjustment,
and
in
this
case, the
indioators should
not
bo considered
reliable.
STALL
WARNING
SYSTEM
10 knots above stall
in all flight conditions.
The stall
warning sys
during
the
preflight
inspection by
placing
a cl
he
vent
opening
and
apptying suction. A sound
will confirm
that
the
system
is
operative.
AVIONICS
SUPPORT
EOUIPMENT
If the
airplane is equipped with avionics,
various avionics
support
equipment
may also
be
installed. Equipment awailable
includes an
avio-
nics cooling
fan,
microphone-headset installations
and control
surfa,ce
static dischargers.
The followi¡rg
pa,ra,gra,phs
disouss
these
items.
Des-
cription
and operation
of
radio
equipment
is cowered in Section
9 of
this
handbook.
AVIONICS
COOLING FAN
An avionics cooling
fan system is
provided
whenever
a factory-
installed
Nav/
Com
radio
is installed. The
system
is designed
to
provide
internal cooling
aír from
a
small
electric fan to
the
avionics
units
and
thereby eliminate
the
possibility
of moisture
conta,mination
usÍng
an
external cooling
air
souroe.
Powor to
the olectric fan is
supplied directly
from
a
"pull-off"
type
30
May 1980 7-3ó