Aeronautica

1.5 ENGINE IGNITION, ELECTRICAL POWER SUPPLY,
AND DISTRIBUTION SYSTEMS (74-00-00).
NOTE
Dual nomenclature is utilized for some components
as an aid to the user since the job
guide nomenclature and schematic diagram nomenclature
in some cases are different.
The ignition system provides constant ignition for main engine
operation and augmentor ignition during augmentor selection.
Theself-contained engine ignition system provides
two electrically independent circuits for engine ignition and
two for augmentor ignition, thereby providing redundant ignition
for the main combustor and augmentor. (See ENGINE
POWER CONTROLS (1.7) for additional description of the
engine generator) The engine ignition system is comprised of
the following components:
a. Right Main Ignitor (7421E3)b. Left Augmentor Ignitor (7421E2)
c. Right Augmentor Ignitor (7421E4)
d. Left Main Ignitor (7421E1)
e. Right Dual Ignition Exciter (7421G1)
f. Left Dual Ignition Exciter (7421G2)
g. Augmentor Light-Off Detector (Light-Off Detector)
(7421A1)
1.5.1 Right Main Ignitor (7421E3). The right main ignitor
(Figure 1-16) is a high voltage ignition device located on the
right side of the combustionchamber at approximately the 4
o’clock position with access through access door 4202. The
ignitor accepts electrical energy from the right dual ignition
exciter through a high tension cable. A gap between the
electrode and ground creates a spark which provides ignition.
1.5.2 Left Augmentor Ignitor (7421E2). The left augmentor
ignitor (Figure 1-16) is a high voltage ignition device
locatedon the left side of the rear fan duct at approximately
the 7 o’clock position with access through access panel 4301.
The ignitor accepts electrical energy from the left dual ig-
74-00-00
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nition exciter through a high tension cable. A gap between the
electrode and ground creates a spark which provides ignition.
1.5.3 Right Augmentor Ignitor (7421E4). The right augmentor
ignitor(Figure 1-16) is a high voltage ignition device
located on the right side of the rear fan duct at approximately
the 5 o’clock position with access through access panel 4305.
The ignitor accepts electrical energy from the right dual
ignition exciter through a high tension cable. A gap between
the electrode and ground creates a spark which provides
ignition.
1.5.4 Left Main Ignitor (7421E1). Theleft main ignitor
(Figure 1-16) is a high voltage ignition device located on the
left side of the combustion chamber at approximately the 8
o’clock position with access through access panel 4103. The
ignitor accepts electrical energy from the left dual ignition
exciter through a high tension cable. A gap between the
electrode and ground creates a spark which provides ignition.
1.5.5 RightDual Ignition Exciter (7421G1). The right
dual ignition exciter (Figure 1-16) is a capacitor dischargetype
exciter located on the right side of the rear fan duct at
approximately the 4 o’clock position with access through
access door 4302. The exciter is a capacitor discharge-type
exciter that has two independent circuits. One circuit provides
electrical energy to the right main ignitor, andthe other
circuit provides electrical energy to the right augmentor
ignitor.
1.5.6 Left Dual Ignition Exciter (7421G2). The left dual
ignition exciter (Figure 1-16) is located on the left side of the
rear fan duct at approximately the 8 o’clock position with
access through access door 4301. The exciter is a capacitor
discharge-type exciter that has two independent circuits. One
circuitprovides electrical energy to the left main ignitor, and
the other circuit provides electrical energy to the left augmentor
ignitor.
1.5.7 Augmentor Light-Off Detector (Light-Off Detector)
(7421A1). The augmentor light-off detector (LOD) (Figure
1-16) is an electrical unit mounted on the augmentor duct.
The LOD detects the presence or absence of flame by using
an ultraviolet sensor tube and...