a. General The fuel system is designed so that fuel is circulating through the filter-separator whenever the system
fuel pump is running. Recycling of fuel enhances the removal of entrained solids and
During operation, periodic checks must be made of the differential pressure (DP) across the filters Water must be
drained from the tank sump before and after each operations.. Also, the air vent valve must be operated
periodically to purge the tank of any air. The required frequency of these operating procedures will be based on
experience gained in operating the system. Factors affecting this frequency will be:
Amounts of water and solids present in the fuel supply.
(a) An increase in the water removed from fuel can be expected during humid or rainy weather
(b) An increase in the amount of solids removed, indicated by an accelerated differential pressure
indication on the DP gage, can be expected when operating in dusty or sandy environment.
Quantity of fuel being dispensedfrom the system.
Duration of fuel system operation.
b. Draining Water From Sump
. (Refer to Figure 2-16).
· When the defrost shroud is used for heating, the shroud and water drain valve may be very hot
Exercise caution to avoid burns.
· Do not allow fuel to came in contact with eyes or skin. Wear protective goggles. Fuels are toxic
and can cause illness or death. If fuel contacts skin or eyes, flush and get medical attention
Drain water from sump (1) by turning handle (2) on the drain valve (3) slowly to the OPEN position. Hold
an empty container under the drain pipe (4) to catch the expelled contaminated fuel.
For disposal of contaminated fuel, refer to FM 10-20.
Allow the water to drain until fuel starts to flow from the drain pipe (4), then turn the handle (2) to the