POWER PLANT
For Training Purposes Only
May 03
18-17
P I L O T T R A I N I N G G U I D E
Ignition System
Description
Two independent alternating current (AC) ignition systems are provided for each
engine. Each ignition system consists of one ignition exciter and one igniter plug.
Ignition system A is powered by the AC Essential Bus. Ignition system B is powered
by the Battery Bus through a static inverter.
Operation
There are three ignition system modes:
Normal -
Prior to engine start, the ignition is armed by selecting either A or B ignition
switch/light at the START/IGNITION panel.When an ignition system is armed, the
corresponding white ARM light illuminates. Ignition is energized upon starter
engagement and is de-energized at starter cutout (55% N
2
). While an ignition system is
energized, the corresponding green ON light illuminates and the IGNITION A(B)
advisory EICAS message appears.
Continuous ignition
- Continuous ignition may be selected by pressing the CONT
ignition switch/light at the START/IGNITION panel. Both ignitions A and B are
energized. When continuous ignition is selected, both green ON lights illuminate and
the IGNITION A/B advisory EICAS message appears.
Continuous ignition must be used during the following flight conditions:
•
takeoff and landings on contaminated runways
•
takeoff with high crosswind components (greater than 10 knots)
•
flight through moderate or heavier intensity rain
•
flight through moderate or heavier intensity turbulence
•
flight in the vicinity of thunderstorms
Auto-ignition (aerodynamic stall protection) -
Automatic activation of continuous
ignition is based upon angle-of-attack (AOA) data. Both systems A and B are
energized by the stall warning computer and remain on until the airplane flight attitude
is corrected.
Activation of the Stall Protection System Test will activate
continuous ignition.
Both ignition systems A and B are disabled on the associated engine when the L (R)
ENGINE FIRE PUSH switch/light is selected. If continuous ignition was in use, the
white ON legend of the CONT switch/light will extinguish, but the green ON lights in
CAUTION
