Hawker Beechcraft Hawker 800XP, Руководство по эксплуатации для пилотов

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Page 2-28
Pilot’s Operating Manual
Original Issue: Feb, 2002
Sub-section 2
ENGINES
Hawker 800XP Pro Line 21
Section III - SYSTEMS DESCRIPTION
Surge Bleed Valve
Under certain conditions, gas turbine engines tend to surge and stall. For each compressor RPM, there
is a relationship between the amount of air flow and the pressure gradient; a disturbance results in the
engine surging. A surge bleed valve protects against this problem. The DEEC controls the position of
the surge bleed valve which is located between the LP compressor and the HP compressor, to prevent
compressor stalls and surges. If the valve opens, compressed air flows into the bypass duct smoothing
out the pressure gradient throughout the engine.
The DEEC normally positions the surge bleed valve fully open for start and idle conditions and fully
closed for high RPM conditions. For transient RPM conditions, however, the DEEC modulates the surge
bleed valve in response to impending stall conditions. With the DEEC off or failed, the surge bleed valve
remains 1/3 open.
Fuel Flow Divider Assembly
The fuel flow divider is between the fuel control unit and the fuel atomizers. During the engine start, the
divider routes fuel at a reduced pressure to the primary atomizers.
As the start sequence continues and the RPM increases, the fuel flow and pressure difference across
the divider orifice increases; fuel passes into the secondary lines that supply the fuel atomizers.
Fuel Nozzles
Each engine uses twelve duplex (primary and secondary) fuel nozzles on two manifold assemblies;
each manifold contains six duplex nozzles. Fuel swirls and breaks into microscopic droplets as it passes
through the atomizer orifice into the combustion chamber. The primary and secondary fuel nozzles
provide a finely atomized fuel spray pattern.
Fuel Heating
The fuel heater permits oil-to-fuel heat exchange to maintain the desired temperature and prevents ice
formation in the fuel system from clogging the fuel pump assembly fuel filter.
A portion of the engine fuel supply is diverted through the fuel heater by the thermostatically operated
anti-ice valve located in the fuel pump. An appropriate amber ENG 1 FUEL or ENG 2 FUEL annunciator,
located on the roof overhead panel and a repeater annunciator located on the MWS panel, will
illuminate when the temperature of the fuel in the associated fuel pump becomes excessive.
ENG 1
FUEL
and/or
ENG 2
FUEL
FUEL
MWS Panel
Overhead Roof Panel