Cessna 177 SERIES Service Manual

c. Remove
the
nut, lockwasher
and
the two
plain
NOTE
washers
securing the wire
which is routed to the
master
switch.
Maintenance
of the electronic
installation
d.
Remove the silicon diode
which is connected
to the cannot
be performed when
using external
battery terminal
and the
coil terminal.
power.
Application
of external
power
e. Remove
the bolt, washer, and
nut securing each side
opens the relay
supplying voltage
to the
of the
battery contactor
to the
battery box.
The contactor
electronic
bus. For
lengthy
ground test-
will now be
free for removal.
ing
of electronic systems,
connect
a well
f. To replace
the contactor,
reverse this
procedure.
regulated
and filtered
power supply
directly
to the
battery side of the
battery contactor.
16-29.
BATTERY
CONTACTOR
CLOSING
CIRCUIT.
Adjust the
supply for
14-volts and
close the
master switch.
16-30.
DESCRIPTION. This
circuit consists ofa
5-amp
fuse,
a resistor and
a diode mounted
on a bracket
on the
NOTE
side of the battery
box.
This serves
to shunt a small
charge
around the battery
contactor so that ground
power may
When using ground
power to start the air-
be used
to close the
contactor when
the battery
is to dead
craft, close
the master
switch
before re-
to energize
the contactor
by itself.
moving the
ground power
plug. This
will
ensure
closure of the
battery contactor
16-31.
GROUND
SERVICE
RECEPTACLE.
and
excitation
of the alternator
field in
the
event
that the battery
is completely dead.
16-32.
DESCRIPTION.
A ground
service
receptacle
is
offered
as optional
equipment
to
permit use
of external
CAUTION
power for cold weather
starting or when performing
lengthy
electrical
maintenance.
A reverse
polarity
pro-
Failure
to observe
polarity
when connecting
tection system
is utilized
whereby
ground power
must
an external
power source
directly
to the bat-
pass through
an external
power contactor
to be connect-
tery,
or directly to
the battery side
of the bat-
ed
to the bus. A silicon
junction diode
is connected
so that
tery contactor,
will damage
the diodes in the
if the ground
power source
is inadvertently
connected
alternator
and other
semiconductor
devices
with a reverse
polarity,
the external
power contactor
in the aircraft.
will not
close. This
feature
protects the
diodes in
the
alternator, and other semiconductor devices, used in
the aircraft
from possible
reverse
polarity
damage.
16-33.
TROUBLE
SHOOTING
-- GROUND
SERVICE
RECEPTACLE.
TROUBLE
PROBABLE
CAUSE
REMEDY
STARTER
ENGAGES
WHEN
Shorted or reversed
diode in
Check
wiring to, and
condition
GROUND POWER
IS CON-
split bus-bar system.
of
diode mounted on the
split
NECTED.
bus relay bracket
adjacent to
the magneto
switch. Correct
wiring.
Replace
diode board
assembly.
GROUND POWER
WILL NOT Ground
service connector
1. Check
for voltage at all
CRANK
ENGINE.
wired incorrectly.
three
terminals of
external
power contactor with ground
power connected and master
switch off. If voltage is pre-
sent on input and coil termin-
als but not
on the output
ter-
minal,
proceed
to step 4.
If
voltage
is present
on the input
terminal but not on the coil
terminal,
proceed to
step 2.
If voltage is
present on all
three
terminals,
check wiring
between
contactor and bus.
2. Check for
voltage at
small
terminal
of ground
service
re-
ceptacle.
If voltage
is not pre-
sent, check ground
service
plug
wiring.
If voltage
is
present,
proceed
to step
3.
Change
8
16-7

Cessna 177 SERIES Specifications

General

Manufacturer	Cessna
Engine Type	Piston
Wingspan	35 ft 6 in (10.82 m)
Seating Capacity	4
Number Built	4, 295
Engine	Lycoming O-360
Horsepower	180 hp
Maximum Takeoff Weight	2, 500 lb (1, 134 kg)