SECTION 8
CESSNA
HANDLING, SERVICE
MODEL 172RG
& MAINTENANCE
items during subsequent servicing operations is recom-
mended.
FUEL
APPROVED FUEL GRADES (AND COLORS) --
100LL Grade Aviation Fuel (Blue).
100 (Formerly 100/130) Grade Aviation Fuel (Green).
NOTE
Isopropyl alcohol or ethylene glycol monomethyl ether
may be added to the fuel supply in quantities not to exceed
1% or .15% by volume, respectively, of the total. Refer to
Fuel Additives in later paragraphs for additional informa-
tion.
CAPACITY EACH TANK -- 33.0 Gallons.
REDUCED CAPACITY EACH TANK (WHEN FILLED TO BOTTOM OF
FUEL FILLER COLLAR) -- 24.0 Gallons.
NOTE
Service the fuel system after each flight, and keep fuel
tanks full to minimize condensation in the tanks.
NOTE
To ensure maximum fuel capacity when refueling, and
minimize cross-feeding when parked on a sloping surface,
place the fuel selector valve handle in either LEFT or
RIGHT position.
FUEL ADDITIVES --
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 may still remain in
solution in the gasoline, it will normally be consumed and go unno-
ticed 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 altitude and low
temperature. 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 system.
8-12
1 July 1979
CESSNA
SECTION 8
MODEL 172RG
HANDLING, SERVICE
& MAINTENANCE
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 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 1%
by volume. Concentrations greater than 1% 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-55MB, if used, must be carefully
mixed with the fuel in concentrations not to exceed .15% by volume.
Figure 8-1 provides EGME-fuel mixing ratio information.
CAUTION
Mixing of the EGME compound with the fuel is extremely
i mportant because a concentration in excess of that recom-
mended (.15% 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
1 July 1979
8-13
