Embraer EMB145 Operation Manual page 1874

POWERPLANT
AIRPLANE
OPERATIONS
MANUAL
ENGINE FUEL SYSTEM
The Engine Fuel System has a distribution and an indicating system.
The distribution system supplies filtered and metered fuel for
combustion. Secondary functions include providing pressurized fuel to
activate the Compressor Variable Geometry (CVG) system, and
providing a cooling medium for lubrication oil. The indicating system
components monitor the fuel supply and are located on the engines.
The engine fuel system comprises a Fuel Pump and Metering Unit
(FPMU), a Fuel Cooled Oil Cooler (FCOC), a Compressor Variable
Geometry (CVG) actuator and fuel nozzles.
FUEL PUMP AND METERING UNIT (FPMU)
The FPMU is an electrical-mechanical, fully-integrated line replaceable
unit which incorporates the engine fuel pumping, filtering, and metering
functions, and operates under authority of the engine FADECs. The
FPMU controls and supplies fuel to the engine nozzles at correct
pressure and flow rate for engine start, correct engine operation,
engine stop, and also controls the compressor variable-geometry
vanes.
The pump system contains a low-pressure centrifugal pump and a
high-pressure gear pump. The centrifugal pump raises the pressure of
incoming fuel high enough to meet the inlet pressure requirements of
the high-pressure pump, with allowances for pressure losses in the fuel
filter and the FCOC. The centrifugal pump also provides vapor-free
fuel to the gear pump.
The main fuel filter, located upstream of the gear pump, protects the
pump metering unit components and fuel nozzles from fuel
contaminants. A fuel flow bypass valve allows continued operation in
the event of complete filter blockage.
A fuel flow pressure relief valve across the pump protects the fuel
system from overpressure conditions.
An air vent valve provides automatic venting of entrapped air or fuel
vapor at the gear pump discharge during engine starting and/or
motoring. The vent valve remains closed whenever the vent solenoid is
not energized, thus preventing fuel leakage through the vent system if
the airplane boost pumps are turned on while the engine is not running.
Page Code
1 01
2-10-10
DECEMBER 20, 2002