Cessna 177 SERIES Service Manual

15-28.
TROUBLE
SHOOTING--
VACUUM
PUMP.
TROUBLE
PROBABLE
CAUSE
REMEDY
OIL
IN DISCHARGE.
Damaged
engine
drive seal.
.Replace
gasket.
HIGH SUCTION.
Suction relief
valve filter
Check
filter for obstructions.
clogged.
Clean or replace
filter.
LOW
SUCTION.
Relief valve
leaking.
Replace relief
valve.
Vacuum
pump
failure.
Substitute
known-good
pump
and check pump suction.
Replace
vacuum
pump.
LOW
PRESSURE.
Safety valve
leaking.
Replace safety
valve.
Vacuum
pump failure.
Substitute
known-good
pump
and
check pump
suction.
Replace vacuum pump.
15-29.
REMOVAL
AND
INSTALLATION
OFCOMPO-
15-31.
VACUUM
RELIEF
VALVE
ADJUSTMENT.
NENTS.
The
various
components
of vacuum
system
A
suction
gage reading
of
5.3 inches
of mercury
is
are secured
by
conventional
clamps,
mounting
screws,
desirable
for
gyro
instruments.
However,
a
range
and nuts.
To remove
a component,
remove mount-
of 4.6 to
5.4 inches
of mercury
is acceptable.
To
ing
screws
and disconnect
inlet and
discharge
lines.
adjust
the
relief
valve, remove
control
air
filter,
When
replacing
a vacuum
system
component,
ensure
run engine
to
1900
rpm on
the ground
and
adjust
re-
connections
are
made
correctly.
Use
thread
lubri-
lief valve
to 5.3
± 1 inch
of
mercury.
cant
sparingly
and only
on male
threads. Avoid
over
tightening
connections.
Before
reinstalling
a
vacuum pump, place mounting pad gasket in position
over
studs.
After
installing
pump,
before
connect-
Do
not exceed
maximum
engine
temperature.
ing plumbing, start
engine and check for evidence
of
oil
in air
discharge.
Be
sure filter
element
is clean
before
installing.
If
reading
drops
noticeably,
install
new
filter
element.
15-30.
CLEANING.
In
general,
low
pressure,
dry
compressed
air
should
be used
in cleaning
vacuum
15-31A
STANDBY
VACUUM
SYSTEM.
system
components
Components
exposed
to engine
oil and dirt,
should
be washed
with
Stoddard
solvent,
15-31B
DESCRIPTION.
A standby
vacuum
system may
then
dried
with a
low pressure
air
blast.
Check
be installed
in the
aircraft.
The system
consists
of a vac-
hose
for collapsed
inner
liners
as
well as
external
uum pump,
driven
by
an electric
motor,
mounted
on the
damage
aft
side of the
firewall,
and associated
hoses.
One hose
is
the
vacuum pump vent hose
and the other connects
to a
CAUTION
manifold
with
the
engine
driven
vacuum
pump,
just
prior to the system relief
valve. A two position
circuit
Never
apply
compressed
air
to lines
or com-
breaker
switch,
mounted
on
the instrument
panel,
con-
ponents
installed
in aircraft.
The
excessive
troles
the
system.
pressures
will damage
gyros.
If an
obstruc-
ted
line is
to be blown
out, disconnected
at
both
ends and blow from
instrument panel
out.
15-14B
Change
8

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)