Cessna 177 SERIES Service Manual

alternate
static source valve (if
installed).
piece of tape over
small hole in lower aft
end of pitot
c. Attach a source of
suction to static pressure
tube, fasten
a piece of rubber or
plastic tubing over
source
opening. Figure
15-3 shows one method
of pitot tube,
close opposite end of tubing
and slowly
obtaining suction.
roll up tube
until airspeed indicator registers in
d. Slowly apply
suction until altimeter
indicates a
cruise range. Secure
tube and after a few minutes
1000-foot increase in altitude,
recheck airspeed
indicator. Any leakage will have
reduced
the
pressure in
system, resulting
in
a lower
CAUTION
airspeed
indication.
Slowly
unroll
tubing
before
removing
it,
so pressure
is reduced
gradually.
Other-
When applying
or
releasing
suction,
do not
wise
instrument
may be
damaged.
If test
reveals
a
exceed
range
of vertical
speed indicator
or
leak
in system,
check
all connections
for tightness.
airspeed indicator.
e. Cut off suction source
to maintain a "closed" 15-15. BLOWING
OUT LINES. Although pitot sys-
system for one minute. Leakage shall not exceed tern is designed to drain down to pitot tube opening,
100 feet of altitude loss as indicated on altimeter.
condensation may collect at
other points in system
f. If leakage rate is within tolerance,
slowly re- and produce a partial
obstruction. To clear line,
lease suction source.
disconnect
at airspeed indicator.
Using low pres-
sure
air, blow
from indicator
end
of line
toward
NOTE pitot tube.
If leakage rate
exceeds maximum allowable,
iCAUTIONI
first tighten
all connections,
then repeat
leakage test.
If leakage rate still exceeds
Never blow through pitot or static lines
maximum
allowable,
use following
procedure.
toward
instruments.
g. Disconnect
static pressure
lines from airspeed
Like pitot lines,
static pressure lines must
be kept
indicator and
vertical speed indicator.
Use
suitable
clear and connections
tight. Static
source sumps
fittings
to connect
lines together
so altimeter is
the collect
moisture and
keep system
clear. However,
only instrument
still connected
into static pressure
when necessary,
disconnect static line
at first in-
system.
strument
to which it is
connected, then
blow line
h.
Repeat leakage
test to check
whether static pres-
clear
with low-pressure
air. Check
all static pres-
sure system
or
the bypassed
instruments
are
cause of
sure
line connections
for tightness.
If hose
or hose
leakage.
If
instruments
are
at fault,
they must
be
connections
are
used, check
for
general
condition
and
repaired
by an "appropriately
rated repair
station"
clamps for
security.
Replace
hose which
have crack-
or replaced.
If static pressure system
is at fault,
ed, hardened or show
other signs of deterioration.
use
following
procedure
to
locate leakage.
i. Attach
a source of positive
pressure to static
15-16. REMOVAL
AND INSTALLATION
OF COM-
source opening.
Figure 15-3
shows one method
of PONENTS.
(Refer
to figure 15-2.)
To remove
pitot
obtaining
positive pressure.
mast remove four
mounting screws on
side of connec-
tor (11) and pull mast
out of connector far
enough to
jCiAUTIONS
disconnect pitot line
(13). Electrical connections to
heater
assembly (if installed)
may be disconnected
Do not apply
positive pressure with
airspeed
through wing access opening
just inboard of
mast.
indicator
or vertical
speed indicator
connect-
Pitot and
static lines are
removed in the
usual manner,
ed to static pressure
system.
after removing
wing access plates,
lower wing fairing
strip and upholstery
as required.
Installation of
j. Slowly
apply positive pressure
until altimeter
tubing will be simpler
if a guide wire is drawn
in as
indicates a 500-foot
decrease
in altitude and main-
tubing
is removed
from wing. The
tubing may be
re-
tain this altimeter
indication while checking
for leaks. moved
intact by drawing it out
through cabin and right
Coat line connections
and static source
flange with
door. Tighten connections
firmly but avoid
over-
solution
of mild soap
and water,
watching for bubbles
tightening
and distorting
fittings. If
twisting of plas-
to locate
leaks.
tic tubing
is encountered
when
tightening
fittings,
k. Tighten
leaking connections.
Repair
or replace
VV-P-236 (USP
Petrolatum)
may be applied
sparingly
parts found
defective.
between tubing
and fittings.
1. Reconnect
airspeed
and vertical
speed indicators
into static pressure
system and repeat
leakage test
per steps "c" thru "f".
15-14.
PITOT SYSTEM INSPECTION
AND LEAKAGE
TEST.
To check
pitot
system
for
leaks,
place
a
15-6 Change 5

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)