Cessna 177 SERIES Service Manual

15-31C. TROUBLE
SHOOTING -- STANDBY
VACUUM PUMP.
TROUBLE
PROBABLE CAUSE
REMEDY
NO
SUCTION GAGE
Circuit breaker
switch
Reset circuit
breaker switch
READING. has
opened. If switch
reopens, check wire
from switch to bus bar for
short. Repair or replace wire.
Defective motor.
Check voltage
input wire
and ground wire. Repair or
replace wires.
Defective
pump.
Check pump operation.
Replace
Pump.
LOW SUCTION GAGE Leak or restriction Check hoses and connections
READING.
between
pump and
for leaks and
obstructions.
suction gage. Install new clamps at connection,
clear or replace hoses.
Relief
valve not
Adjust relief
valve.
properly adjusted.
Defective pump.
Check
pump operation. Replace
pump.
Central air
filter
Clean or replace central air filter.
dirty.
15-31D. REMOVAL. (Refer to figure 15-5A.) 15-31F. LOW VACUUM WARNING SYSTEM. A low
a. Release clamps securing hoses (8) and (11) to pump vacuum warning system may be installed in the aircraft.
(9).
The system consists
of a warning light, mounted
adjacent
b. Cap hoses (8), (11), and pump fittings (10) so dirt can- to the suction gage, a vacuum switch connected in the
not enter system. vacuum hose between the gyros and vacuum filter. Power
c. Make sure circuit breaker switch (1) and
battery to operate the system is supplied
from the circuit
switch are off. breaker bus To test the system, place the master switch
d. Disconnect
motor voltage input wire and ground in
the ON position. The low vacuum lamp will light.
wire. Start aircraft engine and the vacuum switch points will
e. Remove
safety from mounting bolts.
open at approximately 3.0 inches of mercury
vacuum,
f. Release clamp from motor
and the lamp will go out.
g. Support
pump
and motor assembly
and
remove bolts
and washers.
15-32. ENGINE INDICATORS.
h. If pump is to
be removed from motor,
remove nuts
and washers securing pump (9) to motor. 15-33. TACHOMETER.
15-31E. INSTALLATION. (Refer to figure 15-5A.) 15-34. DESCRIPTION. The tachometer is a mechani-
a. If removed,
install pump (9) on motor drive studs
cal indicator driven at half crankshaft speed
by a
and install washers and nuts. flexible shaft. Most tachometer difficulties will be
b. Position pump and motor assembly up against fire- found in the driveshaft. To function properly, shaft
wall (3) and install washers and bolts housing must be free of kinks, dents and sharp bends.
c. Safety wire bolts.
There should be no bend or radius
shorter than six
d. Secure
clamp around motor.
inches, and no bend within three inches
of either ter-
e. Connect motor voltage input
wire and ground wire. minal. If a tachometer
is noisy or pointer oscillates,
f Remove caps from hoses (8), i 11, and fittings
(10) check cable housing for kinks,
sharp bends and dam-
hen install hoses
and clamps. age.
Disconnect cable at tachometer and pull it out
of
g. Turn on battery switch and circuit breaker switch (1) housing. Check for worn spots, breaks and kinks.
then check suction gage
to see that system is opening
prop-
erly. Then turn off switch.
Change 8 15-14C

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)