SOCATA
MODEL TB 20
SECTION 8
AIRPLANE HANDLING, SERVICING
AND MAINTENANCE
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© 1988, 1991, 1992, 1994 to 1996, 1997, 2000 -
socata
- All rights reserved
June 30, 1988
Revision 2
8.12
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 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 in solution 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 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 ispropyl 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 :
– it absorbs the dissolved water from the fuel
– alcohol has a freezing temperature lowering effect.
Alcohol, if used, is to be mixed 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.
