Cessna Skyhawk Owner's Manual page 11

.
MODIFIED FUEL MANAGEMENT
PROCEDURES
CARBURETOR AIR TEMPERATURE
GAGË
With
a
combination
of highly volatile
fuel,
high
fuel
temperature,
high
operating altitude,
and low
fuel
flow rate in
the tank
outlet lines,
there
is
A carburetor air
temperature
gage may be installed in
the
airplane
a
remote possibility
of accumulating
fuel vapor and encountering
power
ir-
to help detect carburetor icing conditions. The gage is marked with a
regularities
on some
airplanes. To minimize
this possibility,
the
follow-
yellow arc between
-15°
and
+5°C.
The yellow are indicates
the carbu-
. ing operating
procedures
are recommended.
retor
temperature
range
where
carburetor icing can occur; a placard on
the
gage
reads "KEEP NEEDLE OUT OF YELLOW
ARC DURING
POSSI¯
(1)
Take-off
and
climb
to
cruise altitude on "both"
tanks.
BLE ICING CONDITIONS.
"
(This
is consistent
with current
recommendations.)
(2)
When reaching
cruise
altitude above 5000 feet
MSL,
promptly
Visible
moisture or high humidity can cause carburetor
ice formation,
switch
the fuel selector
valve from "both"
tanks to
either
the
especially
in idle or low power
conditions.
Under
cruising conditions,
the
"right" or "left"
tank.
formation
of ice is usually
slow,
providing
time to
detect
the
loss of RPM
(3)
During cruise,
use "left"
and
"right"
tank
as required.
caused by
the
ice.
Carburetor
icing during
take-off
is rare
since
the full-
(4) Select "both"
tanks for
landing
as currently recommended.
open throttle condition is less susceptible
to
ice obstruction.
If
the
carburetor air
temperature
gage needle moves into
the
yellow
POWERRECOVERYTECH
NI OUES
arc during
potential carburetor
icing conditions,
or
there is an unex-
plained
drop
in RPM, apply full carburetor
heat. Upon regaining
the
In
the
remote event
that
vapor
is
present in
sufficient amounts
to
original RPM (with heat off), determine by
trial
and error
the
minimum
cause a power irregularity,
the
following
power recovery
techniques
amount of carburetor heat required
for ice-free
operation'
should
be followed:
NOTE
OPERATION ON
A
SINGLE TANK
Carburetor heat should not be applied
during
take-off
unless absolutely necessary
to
obtain
smooth
engine
Should power irregularities occur when operating on a single
tank,
acceleration
(usually
in sub-zero
temperatures).
power
can
be
restored immediately
by switching
to the
opposite
tank.
In addition,
the
vapor
accumulation in the tank
on which
the
power
irregu-
larity occurred will rapidly dissipate itself
such that that tank
will also be
available for normal
operation after it
has been unused
for approximately
one (1)
minute.
OPERATION ON
BOTH
TANKS
Should power
irregularities occur
with
the
fuel selector
on both tanks,
the
following
steps
are
to
be
taken to
restore power:
(1)
Switch
to
a
single
tank
for a period
of
60
seconds.
(2)
Then
switch
to the opposite tank
and
power
will be restored.
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