Ignition System - BOMBARDIER Challenger 601-3A CL-600-2B16 Pilot Training Manual

Fuel Flow Distributor
The fuel flow distributor is a pressure-oper-
ated unit that senses compressor discharge
pressure and fuel pressure at opposite ends of
a linear actuator. The actuator spool has six
rows of three holes in each row. The pressure
differential representing P
moves the spool to align the holes leading to
the 18 fuel injectors in the combustor. The
area of the holes change with spool move-
ment, precisely metering the same amount of
fuel to each of the 18 fuel injectors.
Fuel Drain and Ecology Tank
During engine shutdown, as fuel pressure
drops, a check valve will shut off inlet fuel to
the fuel flow distributor. At the same time,
another check valve will open a drain, and
combustor pressure will force fuel from the in-
jectors and hoses back through the distributor
and out to the ecology drain system. An ejec-
tor in the ecology tank, with motive flow from
the HP fuel pump element, returns fuel to the
inlet side of the LP engine-driven pump.
Operation
Figure 7-7 illustrates operation of the fuel
system in its simplest form. Initial fuel pres-
sure is supplied by the collector tank standby
pump and later by the main ejector through the
open firewall shutoff valve to the LP engine-
driven pump.
The LP pump increases fuel pressure and directs
fuel through the heat exchanger and filter and
to the dual-element HP fuel pump. The #1 HP
element produces the high fuel pressure re-
quired by the FCU. The #2 HP element supplies
the motive flow for main and scavenge ejector
operation. The metering section of the FCU, in
response to the computing section signals, me-
ters fuel through the flowmeter to the fuel man-
ifold. From the fuel manifold, fuel is supplied
in precisely equal amounts through the 18 noz-
zles in the combustor.
During this operation, the variable-geometry
section of the FCU, operating in response to
7-10 CL 601-3A
CL-600-2B16 PILOT TRAINING MANUAL
and fuel pressure
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inputs representing N
discharge pressure, directs fuel pressure to
the variable-geometry actuators to position
the inlet guide vanes and stator to produce a
safe surge margin across the compressor. At
the same time, guide vane and stator position
is fed back to the FCU.
NOTE
When the engine is static, the guide
vanes and stators are at their design
maximum closed position. As the en-
gine starts, the guide vanes' and sta-
tors' position will change until, at high
power setting, both the guide vanes
and stators will be at the design full
open position permitting maximum
airflow through the core engine.

IGNITION SYSTEM

General
The CF34-3A series engine has a dual low
tension, capacitor ignition system.
The ignition system for each engine consists
of an ignitor plug A and an ignitor plug B in
the combustor with each ignitor powered
through its own exciter.
Operation of either ignitor is sufficient to pro-
vide for a normal engine start. The ignitor cir-
cuits for each engine are identified as "ignition
A" and "ignition B."
Ignition Modes
The ignition system has four modes, as follows:
1. Ground start ignition
2. In-flight ignition
3. Continuous ignition
4. Auto (stall) protection ignition
Lt é e
Lt d .
rpm and compressor
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