Cessna 172P - Page 175

CESSNA
MODEL
172P
SECTION
8
HANDLING,
SER,VICING
& MAINTENANCE
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 freezi4g
temperature depressant
effect.
Alcohol,
if used, is to be blended
with
the fuel
in a concentratLonof
IVo
by
volume. Concentratlons
greater
l}r'an IVo are
not recommended
since
they can be detrimental
to fuel tank
materials'
The manner
in whioh 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 bo added
during the
fueling
operation
by
pouring
tho 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-õ566)
or lsopropyl
Alcohol
(Federal
Specification
TT-f-
735a),
Figure 8-1
provides
alcohol-fuel
mixing ratio information.
Ethylene
glycol
monomethyl ether
(EGME)
compound,
in compliance
with
MIL-I-27686
or PhÍIIips PFA-55M8,
if used, must be carefully
mixed
with the fuel in concentrations not to exceed ,t6Vo 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
(.Lõ%o
by
volume
maximum) wiII 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.
3O
May 1980
8- 13