c. The overspeed orifice bleeds Py pressure from
the governing system of the gas producer fuel control.
Bleeding Py pressure at the power turbine governor
gives the fuel control system a rapid response to
1-14. Fuel Pump and Filter Assembly.
a. The fuel pump and filter assembly (figure 1-5)
incorporates a single gear-type pumping element, a
low pressure barrier filter, a filter bypass valve, and a
bypass pressure regulating valve, Fuel enters the
engine fuel system at the inlet port of the pump and
passes through the low pressure filter before entering
the gear element. The filter bypass valve allows fuel to
bypass the filter element if it becomes clogged.
b. The bypass return flow from the fuel control u
passed back to the inlet of the gear element through a
pressure regulating valve which maintains the bypass
flow pressure above inlet pressure, By means of
passages leading to auxiliary filling ports on the
periphery of the gear element, a portion of the bypass
flow is used to fill the gear teeth when vapor-liquid
conditions exist at the inlet to the gear element.
c. The 5 micron nominal 15 micron absolute,
paper filter is located inside the fuel pump assembly
upstream of the gear element. It is retained by a cast
cover attached to the pump housing by two socket
head cap screws. The cover is located on the aft side of
the pump. To minimize fuel spillage during filter
replacement, fuel may be drained through the lower of
Figure 1-5. Fuel Pump and Filter Assembly