MD-11 Flight Crew Operations Manual
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Engines -
Description and Operation
Eng.10.7
When the engine has attained about 45 percent N2, the starter air valve closes and
shuts off air to the starter turbine. As the engine continues to accelerate, a starter
clutch automatically disengages the starter.
An amber light in the respective ENG START switch will remain illuminated
when the valve is not closed.
Fuel Control System
Fuel flow is controlled by the ECU.
The engine FUEL switch supplies electrical power directly to the
Hydromechanical Unit (HMU). The HMU then operates the High Pressure fuel
Shutoff Valve (HPSOV).
A red light in the engine FUEL switch will illuminate if an engine fire condition
occurs. The light will also illuminate during the ENG/APU FIRE test.
Moving the engine FUEL switch to ON starts ignition and fuel provided the ENG
START switch is out and the ENG IGN switch is selected A or B.
The FSC automatically turns on the fuel pumps in tanks 1, 2, or 3 when the
respective ENG START switch is pulled to ON.
Moving any FUEL switch to ON initiates a test of the cargo door indicating
system sensors. The TEST light on the forward overhead panel will illuminate
during the test. If the test is satisfactory, TEST will extinguish. If the test fails, a
CRG DOOR TEST FAIL alert will be displayed.
Fuel flows through the following components:
1. Fuel-oil heat exchanger.
2. Fuel filter.
3. Fuel flow meter.
4. IDG fuel-oil heat exchanger.
5. Fuel metering valve.
6. Fuel nozzles (30).
Fuel flowing through the fuel/oil heat exchanger cools the engine oil and heats the
fuel.
A pressure differential switch is installed across the main fuel filter and will
display an appropriate alert when an impending filter clogging situation exists. If
the filter clogs to a predetermined degree, fuel will bypass the filter to maintain
flow to the engine.
October 02, 2006
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