Pilot's Operating Handbook
Section 8
Handling, servicing and maintenance
Edition 0 - March 05, 2019
Rev. 0
Page 8.7.4
Fuel additives
Fuel used must contain an anti-ice additive conforming to MIL-I-27686 or MIL-I-85470
specification.
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 emulsified 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 use of certain fuels, with high humidity conditions on the ground followed by flight at
high altitude and low temperature. Under these unusual conditions, small amounts of
water emulsified can precipitate from the fuel stream and freeze in sufficient quantities
to induce partial icing of the engine fuel system.
While these conditions are quite rare and will not normally be 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 required to add an ethylene glycol monomethyl ether (EGME or
DIEGME) compound to the fuel supply.
The introduction of an EGME or DIEGME compound into the fuel provides two distinct
effects :
-
it absorbs the dissolved water from the fuel
-
alcohol has a freezing temperature depressant effect.
EGME or DIEGME must be carefully mixed with the fuel in concentration, it must be
between a minimum of 0.06 % and a maximum of 0.15 % by volume. Figure 8.7.3
provides EGME or DIEGME / fuel mixing ratio information.
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CAUTION
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Do not permit the concentrate of EGME or DIEGME to come in contact
with the airplane finish or fuel tank
Mixing of the EGME or DIEGME with the fuel is extremely important.
An excessive concentration (greater than 0.15 % by volume maximum)
will result in detrimental effects to the fuel tanks by deterioration of
protective primer, sealants and seals of system and engine
components. Use only blending equipment recommended by the
manufacturer to obtain proper proportioning.
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PIM - DO NOT USE FOR FLIGHT OPERATIONS
