Cessna SKYHAWK - Carburetor and Fuel System Management; Carburetor Air Temperature Gauge; Modified Fuel Management; Power Recovery Techniques

.
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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