MD-11 Flight Crew Operations Manual
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Engines -
Description and Operation
Eng.10.5
Only one ignitor is required to start the engine. During a ground start, either
ignition (A or B) may be selected with the ENG IGN switches on the forward
overhead panel. When either ENG IGN A or B switch has been pushed, moving
the respective FUEL switch to ON will turn on the corresponding ignitor.
With A or B selected, continuous ignition is provided automatically during
takeoff, landing, and engine anti-ice on (60 seconds only). The selected engine
ignitors automatically shut off when flaps/slats are retracted.
The ignition system indicating lights are integral with the ENG IGN switches and
the ENG START switches. The Miscellaneous Systems Controller (MSC)
provides automatic control of the ignition system.
An ENG IGN OFF light on the forward overhead panel will illuminate if neither
system A or B or the OVRD switch is selected. This indicates that no power is
being supplied to either ignition system.
Selecting ignition system A or B with the ENG IGN switch will:
• Arm the ENG START switches.
• Arm ignition system A or B.
• Send a signal to the APU for 100 percent N1.
• Configure the air and fuel systems for engine start.
With an ignition system selected, the ENG START switch can then be pulled out.
This energizes a coil that holds the switch in that position. The ENG START
switch also energizes the start valve to open and supplies 28-volt dc power to the
ECU.
The Fuel System Controller (FSC) automatically turns on the aft fuel pumps in
fuel tanks 1, 2, or 3 when the respective ENG START switch is pulled or engine
FUEL switch is moved to ON.
When the start valve opens, a light in the ENG START switch will illuminate.
When the engine FUEL switch is moved to on, the MSC supplies 115-volt ac
power to the exciter. A lightning symbol will appear on the EGT display of the
EAD and will remain until 45 percent N2.
As the N2 speed accelerates to 45 percent, the MSC causes the ENG START
switch to pop in. Then the start valve will close, the light in the ENG START
switch will extinguish, and the ignition system will automatically remove power
from the ignitors. The MSC controls the start sequence. If the ENG START switch
latching function in the MSC fails, the switch must be held out until the engine
reaches 45 percent.
The ignition override function can be used for emergency conditions (engine
flameout), for simultaneous failure of ignition systems A and B, or when flying in
heavy turbulence or precipitation.
October 02, 2006
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