SECTION
8
HANDLING,
SERVICE
&
MAINTENANCE
Fuel
Additive
MODEL 402C
Strict adherence to recommended preflight draining instructions as called for in Section 4 will
eliminate
any free
water
accumulations from
the
tank sumps. While small amounts
of
water
Imay
still remain in solution in the
gasoline,
it
will normally be
consumed
and go unnoticed in
the operation
of
the engine.
One
exception to this can
be
encountered when operating under the combined effect of: 1)
use
of certain fuels,
with
2)
high humidity conditions
on
the ground
3)
followed by flight at
high
attitude
and
low
temperature (flight levels
of
20,000 feet or above and temperatures
-28.9°C (-20°F)
or
below).
Under these
unusual
conditions
small
amounts of water
in
solution can precipitate from the fuel stream and freeze in sufficient quantities to induce partial
icing
of
the engine fuel injection system.
While
these conditions are quite rare and will not normally pose a problem to owners and
operators, they do exist
in
certain areas
of
the
world and consequently must be dealt with,
when encountered.
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, 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
1% by volume.
/~~
Concentrations greater than 1% are not recommended since they can be detrimental to fuel
tank materials.
The
manner
;n
which
the
alcohol is added to the fuel is significant because alcohol is most
effective when it is completely dissolved in the fuel.
To
insure 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 transfer this mixture
to the tank prior to the fuel operation.
Any
high quality isopropyl alcohol
may
be used, such as:
Anti-icing fluid (isopropyl alcohol) (MIL-F-5566) or
Isopropyl alcohol (Federal Specification
TI-I-735a).
Figure 8-1 provides additive-fuel ratio mixing information.
I
EGME compound must be carefully mixed with the fuel in concentrations
of
0.10%
minimum '-='-"
.to
0.15%
maximum
by
volume.
8-10
1 November
1979
Revision 5 - 18 March 1998
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