Cessna Skyhawk Owner's Manual page 17

GROUND SERVICE PLUG RECEPTACLE.
cONTROL
WHEEL MAP LIGHT (OPT.)
A ground service plug receptacle
may be installed
to
permit
use
of an
A map light
may
be
mounted
on
the
bottom of
the
pilot's
control wheel.
external power source for cold weather
starting and during
lengthy
main-
The light illuminates
the
lower portion of
the
cabin just forward
of
the
tenance
work on
the
airplane electrical
system (with
the
exception
of elec-
pilot
and
is helpful when checking
maps
and other flight data during night
tronic
equipment). operations. To operate
the
light,
first
turn the
"NAV LIGHTS" switch on,
then
adjust
the
map light's intensity with
the
knurled rheostat knob located
NOTE
at
the
bottom of
the
control
wheel.
Electrical power for the
airplane electrical circuits
is pro- FLASHING
BEACON (OPT).
vided
through
a split
bus bar having all electronic
circuits
on one side of
the
bus and other
electrical circuits on
the The flashing beacon should not be used when flying
through
clouds
or
other side
of
the
bus. When an external power
source is
overcast;
the
flashing light reflected from water droplets or particles
in
connected,
a contactor
automatically opens
the
circuit
to
the
atmosphere, particularly at night, can produce vertigo and loss of
the
electronic
portion
of
the
split bus bar as
a
protection
orientation.
against damage
to the semi-conductors
in
the
electronic
equipment by
transient
voltages from
the
power source.
Therefore,
the
external power source can not be used as CA BI
N HEA T I N
G,
VENT ILA TING A ND
a source of power when checking electronic
components.
DEFROSTING
SYSTEM.
Just before connecting an
external
power source
(generator
type or bat-
For cabin
ventilation,
pull
the
"CABIN AIR" knob out. To raise
the
tery
cart),
the
master switch should be
turned
"ON.
air
temperature,
pull
the
"CABIN HT" knob out approximately
1/4"
to
1/2" for
a small amount
of cabin
heat.
Additional heat is available by
The ground service plug receptacle circuit incorporates
a
polarity
pulling
the
knob out
farther; maximum heat
is
available
with
the
"CABIN
reversal protection.
Power
from
the
external power
source will flow only
HT" knob pulled full out and
the
"CABIN AIR" knob pushed full in. When
if
the
ground service plug is correctly
connected
to the
airplane. If
the
plug is accidentally
connected
backwards, no power will
flow
to the
air
_
no heat
is desired in
the
cabin,
the
"CABIN HT" knob is pushed full in.
plane's electrical
system,
thereby
preventing any damage
to
electrical
Front
cabin heat and
ventilating
air is supplied by
outlet
holes
spaced
equipment.
across
a cabin
manifold
just forward
of
the
pilot's and
copilot's feet.
The battery
and
external power circuits have been designed
to com-
Rear cabin heat and air is supplied by
two
ducts from
the
manifold,
one
pletely eliminate
the
need
to
"jumper" across
the
battery contactor
to
close
extending
down each side of
the
cabin
to
an outlet
at
the front
door post at
it for charging a completely "dead" battery.
A
special fused circuit in
the
floor level. Windshield defrost
air
is also supplied
by
a duct leading from
external power system
supplies
the
needed
"jumper"
across
the
contacts
the
cabin manifold.
so
that
with a "dead" battery and
an
external power source applied,
turn-
ing
the
master switch "ON" will close
the
battery
contactor.
Separate adjustable ventilators
supply additional air; one near each
upper corner
of
the
windshield supplies
air for
the
pilot and
copilot,
and
two
optional ventilators in
the
rear cabin
ceiling supply
air
to the
rear
seat passengers.
STATIC PRESSURE ALTERNATE SOURCE VALVE.
STARTING ENGINE.
A static pressure alternate source
valve may be installed in
the
static
system for
use
when
the
external static source is malfunctioning. During
engine starting,
open
the throttle
approximately
1/8
inch. In
6-2 2-5