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CESSNA
MODEL
172N
SECTION
8
HANDLING, SERVICE
& MAINTENANCE
8- 13
Therefore,
to alleviate the possibility of fuel icing occurring
under
these
unusual conditions, it
is
permissible
to
add
isopropyl alcohol or
ethylene
glycol
monomethyl ether (EGME) compound
to the
fuel
supply.
The
introduction
of
alcohol
or EGME compound
into
the
fuel provides
two distinct
effects:
(1)
it
absorbs
the
dissolved water from
the
gasoline
and (2)
alcohol
has a
freezing temperature
depressant effect.
Alcohol, if
used,
is
to
be
blended
with
the
fuel in
a
concentration
of
l7o
by
volume. Concentrations greater than l7o are not
recommended
since
they
can
be
detrimental to fuel tank materials.
The manner
in which
the alcohol is
added
to the fuel is significant
because
alcohol
is
most
effective
when
it
is
completely
dissolved in the
fuel.
To
ensure proper
mixing,
the
following is
recommended:
1.
For
best
results,
the
alcohol
should
be
added
during
the
fueling
operation by pouring the alcohol directly
on
the fuel stream
issuing from
the
fueling
nozzle.
2. An
alternate method
that may
be used
is to premix
the
complete alcohol
dosage
with
some
fuel
in
a separate
clean
container (approximately 2-3 gallon capacity) and
then
transferring this mixture
to
the
tank prior
to the
fuel
operation.
Any high quality isopropyl
alcohol may
be
used'
such
as
Anti-Icing
Fluid
(MIL-F-5566)
or Isopropyl Alcohol
(Federal
Specification TT-I-
735a).
Figure
8-1
provides alcohol-fuel mixing ratio information'
Ethylene glycol monomethyl ether
(EGME) compound,
in compliance
with
MIL-I-27686
or Phillips
PFA-55M8,
if
used,
must be carefully
mixed
with the fuel in
concentrations not
to
exceed
.157o
by
volume.
Figure
8-1
provides EGME-fuel
mixing ratio information.
CAUTION
Mixing
of
the EGME compound
with
the
fuel
is
extremely
important
because
a
concentration
in
excess
of
that recom-
mended
(.l1Vo
by volume maximum)
will
result in detri-
mental effects to the fuel tanks, such
as
deterioration of
protective primer
and
sealants
and
damage
to
O-rings
and
seals
in
the
fuel system
and engine components.
Use
only
blending equipment that
is recommended by
the
manufac-
turer
to obtain proper proportioning.
1
July
1979
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